Showing posts with label fat burning. Show all posts
Showing posts with label fat burning. Show all posts
Sunday, January 24, 2010
HIIT (on bikes) - why it results in both more fat reduction, and Spot Fat Reduction at That, too than Hearty Steady State
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There are lots of folks espousing the value of HIIT as an effective calorie burner when trying to burn fat. But is there really a special role for HIIT in the fat burning lexicon, or should we just strive to work harder - like 50-75% VO2max - throughout a cardio session? Some more recent work suggests there may be in terms of metabolic activity and even spot fat reduction. But before we go there, let's refresh a bit about HIIT.
The old argument that HIIT burns more calories than Steady State and so is beter has been given a good walloping by Lyle McDonald. Especially in his head to head of steady state with HIIT he pretty persuasively shows that "The intervals only come out a TINY bit ahead if you compare workouts of identical length and even there the difference is absolutely insignificant."
Review: What's HIIT supposed to Do?
Indeed, work from 2008 lead by Shannan E.
Gormley comparing intervals to a decent level of steady state effort did show a benefit for intervals of a sort, but the question for the researchers is what's the optimal time to spend at that peak intensity in an interval to elicit this effect? As cited previously here, the authors state:
So what about fat loss & HIIT, then?
HIIT means high intensity interval protocol. But what is the best HIIT to do if you're tuning it for fat lost first, and anything else second? And does it make a difference if you're dealing with elite athletes or people who are just well enough conditioned so their hearts won't explode if you ask them to go "really hard" for a bit? Is it 60 secs on? 30 off? 60:60? The infamous tabatta on for 20 off for 10 - and remember that was not primarily a fat burning study but an anaerobic/aerobic capacity study.
In 2007 & 2008 a couple studies came out on HIIT from New South Wales as part of some cool PhD work lead by Gail Trapp that i have come to cite frequently about a great HIIT protocol for fat loss and other cool, related benefits that looked explicitly at intervals for fat burning and effects between conditioned and less conditioned participants. Here's the first one, looking at what different HIIT intervals stir up metabolically.
Any type of heart rate elevation triggers some catecholamine response - so does drinking green tea. But what the authors show
here is that both long and short high intensity efforts - sprints in this case - can be effective to trigger greater catecholomine release, but the longer 24 sec sprint with its equivalent longer recovery seems to be better overall for fat mobilization. That's cool. That's actually less work/minute at 24 secs on 36 off than the shorter burst of 8on/12off (24sec vs 40secs of work). Wow. So longer more intense intervals - not necessarily more work - yields higher levels of fat release for fuel - but both the shorties and the longies are good.
Applying these Inervals to Fat Loss. Trapp and Co. then took this finding to a larger cohort of 45 participants (up from 8 and 8), and went longitudinal running a 15 week study. 15 weeks is *good* for 45 people to hang in there.
To be clear, in the second study, gals in the HIIT group did a five minute warm up, followed by 20mins of 8sec sprint followed by 12s of 20-30rpm recovery. The load was continually adjusted over the course of 15 weeks, starting at everyone getting to 20mins at .5kg of resistance. Based on heart rate, the load was upped by .5kg so that the heart effect was consistent as folks got stronger.
The steady state group worked at 60%V02peak - that's a good clip - about 75% maxHR so no slouching there. They worked up from 10mins to 40mins. The mean heart rate of the groups was 168.6 for the HIIT group; 155.7 for the steady state group (participants were 18-30 years old).
As to the fat loss: There was significant FM loss (P less than 0.05) r="−0.58,">This last point is not surprising, based on energy available for fuel from fat relative to bodyfat % (discussed here). The authors come back to this point stating:
Discussion of Findings - Cautious optimism for Intense Intervals
The authors in true geek science-ness don't overegg the results:
more fat available as fuel in the blood ready to be used, Trapp's crew hypothesizes, maybe people doing HIIT just aren't homeostatically tweaked to reach for calorically dense foods - their bodies know they have that covered. That's a really intersting idea. I wonder if doing HIIT closer to meal times enhances this effect, if that's what's going on.
What about this seeming spot reduction? But even if you want to say there are interesting side effects going on with HIIT that are causing these fat loss responses, the authors' key result is this abdominal fat difference. HIIT took OFF some ab fat; Steady state, i'm sorry to say, put some on. Dang.
Here's where exercise type may play an important role in whether or not this spot effect is achieved. The authors postulate the following:
Translating Results to Other Modes? Do these findings translate to other modalities for HIIT - like oh i dunno, maybe kettlebells? Don't know. Perhaps that would be an interesting comparison for bike, hardstyle with it's tension at the top of the swing say, and that hip/core/lat activation, and GS with its more relaxed swing. Do GS/HS differences fall away as the bell weight gets heavier?
In the meantime, the authors offer the following:
While the authors tested their participants with the 8/12 interval, their earlier work with the 24/36 suggests the benefits might be even greater - on a bike, but maybe with a kettlebell or a rowing machine, too.
Take Away: the Skinny on the Fat & HIIT
There are at least two ways to talk about HIIT - in the performance arena, and in fat burning. In performance, there is a small but not insignificant edge to interval work over intense steady state. In fat burning there is a really significant effect. Here's what i think it is.
While the authors make much of the spot fat reduction - and that's not nothing - the more intriguing thing is that *only* the HIIE group lost fat & had their lean body mass go up.
I've cited before work to show that without diet, any weight loss changes, even over 12 weeks of working out are small. In this case, there was no deliberate dietary intervention. So that there was such fat loss without more or less trying dietarily as well is really kinda eye openingly "what the heck?"
So i am intrigued by the authors' speculation about that catecholamine effect and glycerol release and potential effect on let's say homeostasis - a reduced reach for high cal foods, naturally. Wow. That makes HIIE worth looking at from a whole other point that has a whole lot less to do with the calories burned on the bike and the effect of those intervals throughout every other day of the week. And that's only 3*15. What would 3days at 20 or 30 or 40 minutes do? More is not always better - and intervals can be fatiguing but. Hmm.
Related Posts
main refs
There are lots of folks espousing the value of HIIT as an effective calorie burner when trying to burn fat. But is there really a special role for HIIT in the fat burning lexicon, or should we just strive to work harder - like 50-75% VO2max - throughout a cardio session? Some more recent work suggests there may be in terms of metabolic activity and even spot fat reduction. But before we go there, let's refresh a bit about HIIT.The old argument that HIIT burns more calories than Steady State and so is beter has been given a good walloping by Lyle McDonald. Especially in his head to head of steady state with HIIT he pretty persuasively shows that "The intervals only come out a TINY bit ahead if you compare workouts of identical length and even there the difference is absolutely insignificant."
Review: What's HIIT supposed to Do?
Indeed, work from 2008 lead by Shannan E.
Gormley comparing intervals to a decent level of steady state effort did show a benefit for intervals of a sort, but the question for the researchers is what's the optimal time to spend at that peak intensity in an interval to elicit this effect? As cited previously here, the authors state:It should be noted that although interval training groups spend some of their training time at a very high intensity, a similar amount of time is spent at a lower intensity, and therefore the mean intensity of training may not be any higher than that of a continuous training program. In the current study, the interval training group used 5 min each for the work and the recovery phases of the intervals and had an average intensity of 72% HRR, which is slightly less than the 75% HRR of the vigorous [the steady state -mc] group. The work-recovery periods of Helgerud et al.[16] were 4 min at ∼93% HRmax and 3 min at 70% HRmax, for a mean intensity of 83% HRmax in the interval group, whereas one of the continuous groups used 85% HRmax. Warburton et al.[37] used 2 min at 90% HRR and 2 min at 40% HRR for the work and the recovery phases, yielding a mean intensity of 65% HRR in the interval group, and had the continuous training group use 65% HRR. Wisloff et al.[38] used 4-min work phases at ∼93% HRmax and 3-min recovery phases at 60% HRmax, for a mean intensity of 79% HRmax in the interval group, and used ∼73% HRmax in the continuous training group. Despite the similarity of mean intensity between the interval and the continuous training groups, the interval groups in all of these studies experienced greater improvements in aerobic fitness after training. Therefore, although intensity is a key variable in cardiorespiratory training (as shown by comparing the two continuous training groups in this study), the mean intensity may not be as important as the highest intensity that is used for a significant portion of the training. A topic for future research is to determine what portion of training should be done at high intensities and using what work-recovery periods to obtain the greatest resultsThe above is looking not at fat loss effects of intervals, but training to enhance oxidative capacity for performance. More recently even really brief intense bouts of exercise (like 6 mins a week of effort compared with hours of steady state for the same physiological effect as hours of 60% MaxHR), there are similar kinds of performance benefits. So, there seem to be some performance optimization benefits from (a) looking at finding the right balance of peak intensity to recovery for work sessions and (b) looking at supramaximal efforts that may have similar effects in less time. Again, that's performance, not fat loss, and in the former case, we are talking really small degrees of difference.
So what about fat loss & HIIT, then?
HIIT means high intensity interval protocol. But what is the best HIIT to do if you're tuning it for fat lost first, and anything else second? And does it make a difference if you're dealing with elite athletes or people who are just well enough conditioned so their hearts won't explode if you ask them to go "really hard" for a bit? Is it 60 secs on? 30 off? 60:60? The infamous tabatta on for 20 off for 10 - and remember that was not primarily a fat burning study but an anaerobic/aerobic capacity study.
In 2007 & 2008 a couple studies came out on HIIT from New South Wales as part of some cool PhD work lead by Gail Trapp that i have come to cite frequently about a great HIIT protocol for fat loss and other cool, related benefits that looked explicitly at intervals for fat burning and effects between conditioned and less conditioned participants. Here's the first one, looking at what different HIIT intervals stir up metabolically.
Am J Physiol Regul Integr Comp Physiol. 2007 Dec;293(6):R2370-5. Epub 2007 Sep 26.Fat Mobilization: Freed for the Burning. Ah ha you say, there's no fat loss measured here. Right. But what IS measured here is catecholamine activation. Those threat response fight or flight hormones are what mobilize fat to get burned, baby burned. And from these the authors suggest a correlation to the level of catecholamine released and the level of glycerol to be found in the blood stream. In other words, higher degree of intensity, greater catecholamine release, more fat mobilised to be used for fuel.
Metabolic response of trained and untrained women during high-intensity intermittent cycle exercise.
Trapp EG, Chisholm DJ, Boutcher SH.
School of Medical Sciences, Faculty of Medicine, Univ. of New South Wales, Sydney 2052, Australia. e.trapp@unsw.edu.au
The metabolic response to two different forms of high-intensity intermittent cycle exercise was investigated in young women. Subjects (8 trained and 8 untrained) performed two bouts of high-intensity intermittent exercise: short sprint (SS) (8-s sprint, 12-s recovery) and long sprint (LS) (24-s sprint, 36-s recovery) for 20 min on two separate occasions. Both workload and oxygen uptake were greater in the trained subjects but were not significantly different for SS and LS. Plasma glycerol concentrations significantly increased during exercise. Lactate concentrations rose over the 20 min and were higher for the trained women. Catecholamine concentration was also higher postexercise compared with preexercise for both groups. Both SS and LS produced similar metabolic response although both lactate and catecholamines were higher after the 24-s sprint. In conclusion, these results show that high-intensity intermittent exercise resulted in significant elevations in catecholamines that appear to be related to increased venous glycerol concentrations. The trained compared with the untrained women tended to show an earlier increase in plasma glycerol concentrations during high-intensity exercise.
Any type of heart rate elevation triggers some catecholamine response - so does drinking green tea. But what the authors show
here is that both long and short high intensity efforts - sprints in this case - can be effective to trigger greater catecholomine release, but the longer 24 sec sprint with its equivalent longer recovery seems to be better overall for fat mobilization. That's cool. That's actually less work/minute at 24 secs on 36 off than the shorter burst of 8on/12off (24sec vs 40secs of work). Wow. So longer more intense intervals - not necessarily more work - yields higher levels of fat release for fuel - but both the shorties and the longies are good.Applying these Inervals to Fat Loss. Trapp and Co. then took this finding to a larger cohort of 45 participants (up from 8 and 8), and went longitudinal running a 15 week study. 15 weeks is *good* for 45 people to hang in there.
Int J Obes (Lond). 2008 Apr;32(4):684-91. Epub 2008 Jan 15.
The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women.
Trapp EG, Chisholm DJ, Freund J, Boutcher SH.
Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia. e.trapp@unsw.edu.au
OBJECTIVE: To determine the effects of a 15-week high-intensity intermittent exercise (HIIE) program on subcutaneous and trunk fat and insulin resistance of young women. DESIGN AND PROCEDURES: Subjects were randomly assigned to one of the three groups: HIIE (n=15), steady-state exercise (SSE; n=15) or control (CONT; n=15). HIIE and SSE groups underwent a 15-week exercise intervention. SUBJECTS: Forty-five women with a mean BMI of 23.2+/-2.0 kg m(-2) and age of 20.2+/-2.0 years. RESULTS: Both exercise groups demonstrated a significant improvement (P<0.05) in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat and fasting plasma insulin levels. There was significant fat loss (P<0.05) in legs compared to arms in the HIIE group only. Lean compared to overweight women lost less fat after HIIE. Decreases in leptin concentrations were negatively correlated with increases in VO(2peak) (r=-0.57, P<0.05) and positively correlated with decreases in TBM (r=0.47; P<0.0001). There was no significant change in adiponectin levels after training. CONCLUSIONS: HIIE three times per week for 15 weeks compared to the same frequency of SSE exercise was associated with significant reductions in total body fat, subcutaneous leg and trunk fat, and insulin resistance in young women.
To be clear, in the second study, gals in the HIIT group did a five minute warm up, followed by 20mins of 8sec sprint followed by 12s of 20-30rpm recovery. The load was continually adjusted over the course of 15 weeks, starting at everyone getting to 20mins at .5kg of resistance. Based on heart rate, the load was upped by .5kg so that the heart effect was consistent as folks got stronger.
The steady state group worked at 60%V02peak - that's a good clip - about 75% maxHR so no slouching there. They worked up from 10mins to 40mins. The mean heart rate of the groups was 168.6 for the HIIT group; 155.7 for the steady state group (participants were 18-30 years old).
As to the fat loss: There was significant FM loss (P less than 0.05) r="−0.58,">This last point is not surprising, based on energy available for fuel from fat relative to bodyfat % (discussed here). The authors come back to this point stating:
High-intensity intermittent exercise training had a marked effect on fat levels for some individuals and a moderate effect for others. The correlation (r=0.58, P less than 0.01)43, 44 The four moderate fat loss responders in the HIIE group (women who had a 3% or less decrease in total fat) possessed significantly lower initial FM than the other women. With the four lean women removed, the mean fat loss in the HIIE group was 3.94±0.91 kg resulting in a 4.3% decrease in body mass and a 14.7% decrease in total FM. This 3.94-kg fat loss compares favorably to the 1.15-kg weight loss reported in a recent meta-analysis of the effects of SEE on weight loss.That all sounds good and reasonable and wonderful, but then comes the particularly interesting bits - gosh what would almost seem like spot fat reductions:
High-intensity intermittent exercise led to a significant decrease (P less than 0.05) in central abdominal fat (−0.15plus or minus 0.07 kg), whereas the SSE and CONT groups had nonsignificant increases in central abdominal fat (SSE group, +0.1 plus or minus 0.08 kg; CONT group, +0.03 plus or minus 0.04 kg).So more weight off the gut area in HIIT, legs and trunk (other newer work (like this one Nov 08 lead by Irving, and this one Aug 09 lead by Coker ) has seen similar results with gut fat). Intriguingly all groups put on fat in the arms (but not a lot). Indeed, the gut fat loss the authors cite as THE finding of the study. Even more, they state
Despite exercising half the time, HIIE subjects in the present study lost 11.2% of total FM with SSE subjects experiencing no fat loss.That's a pretty big difference between the two groups
Discussion of Findings - Cautious optimism for Intense Intervals
The authors in true geek science-ness don't overegg the results:
Collectively, these results demonstrate that intermittent sprinting compared to SEE is a more effective and efficient way of controlling body composition. However, our estimates of energy expenditure and intake lack sufficient precision to comfortably conclude that energy balance was unaffected in the HIIE condition. Thus, it is feasible that the change in FM that occurred in HIIE may have been influenced by unreported changes in diet. Indeed, HIIE-induced suppressed diet intake may be one of a number of possible factors underlying the fat loss effect of HIIE.11 For example, HIIE may have suppressed appetite or decreased attraction for energy-dense foods.24, 25 Another explanation for the HIIE fat loss effects is that this type of exercise may result in enhanced lipid utilization. Prior research in our laboratory has shown that lipid release, as indicated by blood glycerol levels, gradually increased over 20 min of HIIE.20 Catecholamine levels in this study were also found to be significantly elevated after HIIE.20Free Fat. I love this! Because of that catecholomine hit we saw earlier, and because there's
more fat available as fuel in the blood ready to be used, Trapp's crew hypothesizes, maybe people doing HIIT just aren't homeostatically tweaked to reach for calorically dense foods - their bodies know they have that covered. That's a really intersting idea. I wonder if doing HIIT closer to meal times enhances this effect, if that's what's going on. What about this seeming spot reduction? But even if you want to say there are interesting side effects going on with HIIT that are causing these fat loss responses, the authors' key result is this abdominal fat difference. HIIT took OFF some ab fat; Steady state, i'm sorry to say, put some on. Dang.
Here's where exercise type may play an important role in whether or not this spot effect is achieved. The authors postulate the following:
It is considered that spot reduction (that is, deliberately reducing fat stores in specific areas of the body) is not possible, and the body will mobilize preferentially those stores with the highest concentrations of adipose cells.36, 37, 38 There is evidence in the current study that this principle may not apply to every exercise modality. In HIIE, where work is done primarily by the musculature of the legs and the trunk muscles act as stabilizers, there was a decrease in FM and an increase in lean mass, which summated to a significant change in percentage of fat in these two regions. This was not the case with the SSE group.So where work triggers core stabilizers to get that extra intensity, there may be a seeming spot fat loss effect. It's also interesting to note that only the HIIT group had lean body mass increase.
Translating Results to Other Modes? Do these findings translate to other modalities for HIIT - like oh i dunno, maybe kettlebells? Don't know. Perhaps that would be an interesting comparison for bike, hardstyle with it's tension at the top of the swing say, and that hip/core/lat activation, and GS with its more relaxed swing. Do GS/HS differences fall away as the bell weight gets heavier?In the meantime, the authors offer the following:
In conclusion, 20 min of HIIE [on a bike - mc] , performed three times per week for 15 weeks compared to the same frequency of 40min of SSE exercise was associated with significant reductions in fasting insulin, total body fat, subcutaneous leg fat and abdominal fat.
While the authors tested their participants with the 8/12 interval, their earlier work with the 24/36 suggests the benefits might be even greater - on a bike, but maybe with a kettlebell or a rowing machine, too.
Take Away: the Skinny on the Fat & HIIT
There are at least two ways to talk about HIIT - in the performance arena, and in fat burning. In performance, there is a small but not insignificant edge to interval work over intense steady state. In fat burning there is a really significant effect. Here's what i think it is.
While the authors make much of the spot fat reduction - and that's not nothing - the more intriguing thing is that *only* the HIIE group lost fat & had their lean body mass go up.
I've cited before work to show that without diet, any weight loss changes, even over 12 weeks of working out are small. In this case, there was no deliberate dietary intervention. So that there was such fat loss without more or less trying dietarily as well is really kinda eye openingly "what the heck?"
So i am intrigued by the authors' speculation about that catecholamine effect and glycerol release and potential effect on let's say homeostasis - a reduced reach for high cal foods, naturally. Wow. That makes HIIE worth looking at from a whole other point that has a whole lot less to do with the calories burned on the bike and the effect of those intervals throughout every other day of the week. And that's only 3*15. What would 3days at 20 or 30 or 40 minutes do? More is not always better - and intervals can be fatiguing but. Hmm.
Related Posts
- Kettlebells and Cardio - it doesn't have to be VO2max all the time
- Viking Warrior Conditioning, the Review with Kenneth Jay
- Does Cardio interfer with Strength work? How 'bout No
- Running the bells - hill workouts with kettlebells
- Weight loss doesn't work without Diet - really [story 1, story 2]
- Fat, the amazing fuel.
- Getting a handle on the habits of thinner peace (as martha beck calls it)
main refs
Trapp, E., Chisholm, D., Freund, J., & Boutcher, S. (2008). The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women International Journal of Obesity, 32 (4), 684-691 DOI: 10.1038/sj.ijo.0803781Tweet Follow @begin2dig
GORMLEY, S., SWAIN, D., HIGH, R., SPINA, R., DOWLING, E., KOTIPALLI, U., & GANDRAKOTA, R. (2008). Effect of Intensity of Aerobic Training on VO2max Medicine & Science in Sports & Exercise, 40 (7), 1336-1343 DOI: 10.1249/MSS.0b013e31816c4839
Trapp, E., Chisholm, D., & Boutcher, S. (2007). Metabolic response of trained and untrained women during high-intensity intermittent cycle exercise AJP: Regulatory, Integrative and Comparative Physiology, 293 (6) DOI: 10.1152/ajpregu.00780.2006
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Tuesday, August 18, 2009
The Advantage of an Office Door: A Work Up for a Carb Up
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Ever stolen a work out during the day, or snuck one in? Do you have to go to the gym to do it? At work, i have the privilege of an office with a door on it such that when it's shut, no one can see in, except the workers in the building going up right across from me. We wave at each other from time to time. when they're way hi up on their lego like structures. But now since they're all off for lunch, it is fine and proper to change my shirt and shorts for sweatable attire and commence a pre-lunch ritual: the carb burn pre load work up.
Yes work up: i am working up to a happy feeding time, knowing i'm not just eating cuz i'm a bit peckish; i'm refurbishing my muscles glycogen stores when they'll be happiest to receive them.
To achieve this today, i decide to do a 15:15 vo2max workout as per Viking Warrior Conditioning (reviewed here).
But then, mid workout, what happens? i start to feel a callus go - for those of you who do this kind of thing you know what i mean. I don't want a tear - i'm about to go away on a break and while i suppose that would be the ideal time to have a tear (if one must) i think i'd rather not. Band aids etc, no fun. Phooey.
So i do the a-typical smart thing and stop my vo2max work with a 12kg and transition gracefully into an on-the-fly adapted 8on 12 off session of swings for the next 11 minutes with a 24kg. Perfect form, perfect form. Every rep a perfect rep. My word, 12 secs post kettlebell seems much shorter post a kettlebell set than it does on the bike.
This protocol is based on one developed by Trapp and co for eliciting optimal fat burn in women of both athletic and not so athletic backgrounds. 20mins of 8/12 intervals seemed to be a sweet spot for fat burning.
As for the application of the above with a heavy kb, i can say after the 11th minute, it seems i may have found a way to test for a new max heart rate. Cuz that was higher than on a bike and not maximal. I was still standing. Hmm. On the fat loss, well i don't know. It's more effortful than on a bike. May try again with a 20kg, just to calibrate. Interesting enough to want to give it a go again.
Feeling very pleased to have done this work up.
Clean up; re-dress and regroup. Lunch becomes a happy happy thing. A definite re-fuel. Ideally if i'd been thinking straight i would have grabbed a lighter bell just to do some more cool down swings to get a bit more fat flamed off before it re-esterfies from sitting down again.
So what's the take away here:
If you'd like more info on feeding up and why post workout, and what that has to do with muscles, here' a bit more in a review i did of precision nutrition's individualization/carb tolerance.
Now for the post happy lunch cup of tea... Tweet Follow @begin2dig
Yes work up: i am working up to a happy feeding time, knowing i'm not just eating cuz i'm a bit peckish; i'm refurbishing my muscles glycogen stores when they'll be happiest to receive them.
To achieve this today, i decide to do a 15:15 vo2max workout as per Viking Warrior Conditioning (reviewed here).
But then, mid workout, what happens? i start to feel a callus go - for those of you who do this kind of thing you know what i mean. I don't want a tear - i'm about to go away on a break and while i suppose that would be the ideal time to have a tear (if one must) i think i'd rather not. Band aids etc, no fun. Phooey.
So i do the a-typical smart thing and stop my vo2max work with a 12kg and transition gracefully into an on-the-fly adapted 8on 12 off session of swings for the next 11 minutes with a 24kg. Perfect form, perfect form. Every rep a perfect rep. My word, 12 secs post kettlebell seems much shorter post a kettlebell set than it does on the bike.
This protocol is based on one developed by Trapp and co for eliciting optimal fat burn in women of both athletic and not so athletic backgrounds. 20mins of 8/12 intervals seemed to be a sweet spot for fat burning.
Metabolic response of trained and untrained women during high-intensity intermittent cycle exercise.
School of Medical Sciences, Faculty of Medicine, Univ. of New South Wales, Sydney 2052, Australia. e.trapp@unsw.edu.au
The metabolic response to two different forms of high-intensity intermittent cycle exercise was investigated in young women. Subjects (8 trained and 8 untrained) performed two bouts of high-intensity intermittent exercise: short sprint (SS) (8-s sprint, 12-s recovery) and long sprint (LS) (24-s sprint, 36-s recovery) for 20 min on two separate occasions. Both workload and oxygen uptake were greater in the trained subjects but were not significantly different for SS and LS. Plasma glycerol concentrations significantly increased during exercise. Lactate concentrations rose over the 20 min and were higher for the trained women. Catecholamine concentration was also higher postexercise compared with preexercise for both groups. Both SS and LS produced similar metabolic response although both lactate and catecholamines were higher after the 24-s sprint. In conclusion, these results show that high-intensity intermittent exercise resulted in significant elevations in catecholamines that appear to be related to increased venous glycerol concentrations. The trained compared with the untrained women tended to show an earlier increase in plasma glycerol concentrations during high-intensity exercise.
As for the application of the above with a heavy kb, i can say after the 11th minute, it seems i may have found a way to test for a new max heart rate. Cuz that was higher than on a bike and not maximal. I was still standing. Hmm. On the fat loss, well i don't know. It's more effortful than on a bike. May try again with a 20kg, just to calibrate. Interesting enough to want to give it a go again.
Feeling very pleased to have done this work up.
Clean up; re-dress and regroup. Lunch becomes a happy happy thing. A definite re-fuel. Ideally if i'd been thinking straight i would have grabbed a lighter bell just to do some more cool down swings to get a bit more fat flamed off before it re-esterfies from sitting down again.
So what's the take away here:
- glad i've FINALLY gotten to a place where i can change an envisioned workout in order to keep working out, rather than obsessively have to stick with ONE routine because, who's keeping track again? oh? just me? right-o.
- doing short intervals with a heavy kb is an intriguing workout from both a cardiac and potential fuel burning perspective.
- remember to stash chalk at work, too: a few more minutes and that 24 would have been sailing out of the office towards the new building. Even though that's rather a pleasant thought - sort of like shooting a canon at an enemy battlement, the consequences would not be pretty.
- the snatch grip to avoid calluses in fast repeats is a skill to be learned - still
If you'd like more info on feeding up and why post workout, and what that has to do with muscles, here' a bit more in a review i did of precision nutrition's individualization/carb tolerance.
Now for the post happy lunch cup of tea... Tweet Follow @begin2dig
Friday, August 7, 2009
Respect the Fat: An overview of Fat Burning Goodness
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We hear it all the time: fat is bad; we have too much; we need to shed the fat. Yes sure, leaner is better for health. But that doesn't mean either that fat is bad or that ingesting the right kinds of fats (yup, there are kinds) is bad. Quite the opposite.
In fact, fat is our biggest and one might argue most versatile sources of fuel. It also makes up the shell of every cell in our body, and is part of a host of other essential for life processes that happen inside us. But the focus of this post is on how fat contributes to providing us with the fuel we need and use in every breath we take.
Fat is amazing. It's the most abundant fuel source in the
body.
Every time we breath we're using fat to help take care of the energy needs of our bodies, whether thats muscular activity of lifting something, or the chemical activity of digesting something, or the transport activity of moving something from one cell to another.
In each of these cases, Fat contributes the lion's share of the energy to our physical processes. We couldn't live without it: adipose tissue affords protection to our body's various systems as well as immediate fuel storage sources; the membranes of cells are part fat and enable standard operations of the heart and lungs to get nutrients throughout our systems. And, it's also an energy reserve. Like having a bunch of batteries in the cupboard ready for when the smoke alarm or flashlight fails. Swap out the old cells put in the new.
Despite these great capacities, most of us want to shed some extra weight. Indeed, we know that it's our incredible ability to store fuel resources that works to our socio-cultural detriment in a society where fuel-as-food is readily and cheaply abundant. We put on extra weight. We carry reserves in excess of what we need given the ready abundance of fuel around us. And there are some pretty nasty health costs to carrying around that much surplus fuel, too. Type II diebetes, metabolic syndrome, additional load on joints, etc.
And so we look for ways to burn it off.
The goal of this article is to take a 50thousand foot view (ie really simplified view) at part of what's going on with that burn off, and why therefore fat is our super fuel and seemingly super nemesis.
What i mean by simplified view? Here's a map of the metabolic process:
A metabolic map, indicating the reactions of intermediary metabolism and the enzymes that catalyze them. Over 500 different chemical intermediates, or metabolites, and a greater number of enzymes are represented here. ((c) 1997 20th edition, designed by and courtesy of D. E. Nicholson, University of Leeds , U. K., and the Sigma Chemical Co. )
We're considering a wee fraction of this entire process, and only part of what's going on as illustrated below (source):
The three stages of catabolism. Stage I: Proteins, polysaccharides, and lipids are broken down into their component building blocks, which are relatively few in number. Stage II: The various building blocks are degraded into the common product, the acetyl groups of acetyl-CoA. Stage III: Catabolism converges to three principal end products: water, carbon dioxide, and ammonia
These maps help to get that this is complex cool stuff. we are amazing. The above maps let us ask the question - how do we get the good stuff out of fat to use? and to appreciate how a little bit of fat goes a really really long way. To get to that, we need to consider what energy from fat means. And that means taking a look at ATP, the primal fuel block (what fat and other nutrients in large part become), and also situating fat a bit relative to other nutrients like carbs and protein in this fuel-making process (nothing shines out like a comparison). We'll take a wee look at what can increase the fat burn in cells (mitochondria) and finally, where this should lead: why fat, while it burns all the time, is still a challenge to shed.
Energy from Fat
Anyone who's spent time counting calories likely knows that the standard wisdom about calories is that carbs are 4kcal per gram and so is protein. Fat however is 9kcal per gram. Remember a calorie is a measurement of energy: the amount of energy to raise 1 g of water 1 degree.
Right from the outset, it looks like fat has the advantage in providing us with more energy than either carbs or protein. Looks like about twice as much. That's true. But what is really cool about fat is that it gives us more useable fuel for the body to do its lifting, chemical processing and transporting than we get from protein or carbs, and that's in terms of it's translation from a fat to ATP.
ATP
ATP or adenosine triphosphate. ATP is what powers all the energy in cells.
We hear a lot about ATP in the body building world and general strength training: in big lifts the point of that long recovery is to replenish phosphocreatine stores that can make a little bit of ATP available without the presence of oxygen - like when we hold our breath, or exhale out, to do that big dead lift, or keep our head under water for that 50m sprint to the end of the pool. 1 molecule of phosophocreatine when it's broken down into ATP yields only a few ATP molecules. That's not a lot for intense work, but it can re-synthesize quickly for short 30sec bursts.
But what about for efforts that last longer than 30secs? Then we start getting into carb and fat world. Protein is used for very little energy - 2-5% - it has other jobs. If no other source of fuel is available for energy - no carbs say after a workout and you use protein - a chunk of that protein will be used as fuel - transformed into carb-like fuel for replenishing energy stores. And when folks take on more protein than can be used for any current physical requirements, protein will be translated into fat.
Digression on Protein and Starvation
Here's the other thing about Protein as fuel: some folks find that when they're working out and dieting at the same time, it seems their fat loss stalls out. That's a well-studied phenomena that if the body has fat for fuel, and it feels like it's being starved (only recieving 50% or more of the needed cals for maintenance), it will horde fat for as long as possible, and will start to catabolize (break down) other sources in our bodies for fuel. Protein from muscle is a goody.
So often folks starting an exercise program after they've started dieting need to INCREASE their calories a bit to off set starvation.
Now if someone persists at starvation levels long enough, the weight will come off. The famous Minnesota experiment demonstrated this action.
So back to ATP - and ATP from our nutrients.
The body stores only 80-100g of ATP at a time. So it has to synthesize ATP all the time.
A huge point of taking in food is to convert these fuels into ATP. Without going into the detail here, here's where fat comes into its own: a molecule of glucose (stuff from carbs generally), depending on the source, produces 36 or 38 molecules of ATP. 1 fatty acid molecule (derived from fat sources) produces 460 molecules of ATP. That's considerably more than 10 times the amount of usable fuel for muscular, chemical and transport activities than carbs.
Why is this? Basically the way fat breaks down more of it can be translated into ATP than carbs. If you look at the second big map above, you'll see that carbs have to go through three intermediate steps before they get to acetlyCoA. Fat can go pretty much directly to that stage.
Fewer steps, less stuff used for other things than ATP...
The process of how these various translations of a food into a bundle of energy occurs is really cool. It's a testament to how adaptable we are. For instance if we don't have enough carbs in our bodies for the jobs carbs are used to do - like feed our brains and liver - the body will translate fat into carb substitute. This process is the subject of books like Lyle McDonald's excellent review called the Ketogenic Diet.
Why bother with carbs at all if Fat is so awesome? and is that the secret of these "low carb" diets?
Fat burns in the flame of carbohydrate.
One of the best ways to stoke fat to burn is in the presence of carbs - this has to do with stuff in the Citric Acid Cycle. When carbs aren't present and the body has to go ketogenic to use fats instead, well, it can do it, but it's not necessarily optimal. You can skip this next bit if you wish but some folks have asked for a bit more explanation of what this Flame means. So the following digression:
And fat in something called "slow glycolosis" (part of the Krebs Cycle, pictured as the ring in the second figure above) loves carbs to let it burn baby burn. Now before anyone jumps on me, no Fat does not REQUIRE carbs to help it break down into the stuff that enters the KC to become ATP but it is sort of the path of least resistance, perhaps, if i can put it that way.
And just to repeat what may well be obvious to all:
fat burns as fuel via the happily fairly constant activity of breathing. Fat is "oxidized" to break
down into fuel. This oxidation takes place in the mitochondria of the cell. Hence it's important to have rather a lot of it as we breath so much.
Aside: Fat Burners. We may also recall that the discussion last week about super intense low volume 6min. workouts a week created as many new mitochondrias (ie fat burners) as did 1-2 hours a week of steady state cardio. Want to enhance fat burning? combined with diet, enhancing mitochondira helps.
I dunno, just thinking about all the things a bit of fat does it once again strikes me how incredibly amazing we are. So versatile. We can fuel ourselves up with just about anything we ingest. Our systems have preferences but can adapt to circumstances. Wild.
And fat is wild because it does so much for us.
Losing/Burning Fat - Hard Homeostatic or Hard Habit?
But you may be asking if we're burning fat (converting it into ATP pretty much constantly), why are we Fat? Why is fat hard to lose?
I guess the question might be reframed as is fat hard to lose?
What is hard, it seems, when food is so easily available to us, in ways historically unprecedented, we follow our ancient wiring and we eat. We want to load up for the lean times. But we don't live in scarcity. Access to ready prepared food continues to increase. Our need for these responses to horde up are less appropriate.
see
So perhaps what's hard is the habits around caloric restriction: being patient enough with ourselves to learn new habits to support some caloric restriction to lose weight. To be patient with ourselves that fat loss takes time. While the inital excess fat may come off faster, those last ten pounds are killers, and there are reasons for this too that i've discussed elsewhere.
And without habits to support ongoing lean attitudes, then how do we keep the weight coming off? and then how do we maintain our goal weight?
I've said it before, its this need for habits around food rather than specific diets that i like precision nutrition. It supports habits.
Rewiring for Fat: Love your Fat; Burn your Fat; Respect the Fat
So while we are wired to grab store and horde fuel, we can adapt our behaviours to be lean in the face of abundance. Once we start turning on those habits, we do need to tune them to optimize fat burning. The basic part of fat burning is to get the balance of eat less right with whatever activity one is at, so one stays productively above starvation level.
Being patient with ourselves to learn what that sweet spot mix of caloric restriction and workout effort to optimize fat burning - if that's the priority - takes time, patience, and a strategy to be able to assess if what's being tried works. Again, i'll say i like precision nutrition becuase it has a method called an Individualization Guide to support exactly that process.
Calorie Note: Why only 3500kcals to drop a Pound of Fat?
Some folks have noticed a seeming discrepancy between cals in a pound of fat and that there are fewer calories to burn a pound of "fat"
I'm still looking for sources on this, but here's the argument: let's start with the basics.
1g of fat = 9kcal
so 1kg of fat =9000kcal
9000/2.2 = 4091kcal / pound of fat (1kg/2.2=1lb)
Apparently a pound of human fat is made up of 10% water + 5% other materials that aren't digested - i need sources to support this, but if we go with that for a moment
4091 -15%= 3477.35
That's approx 3500kcals.
One other frequently quoted statement on the web is "Human fat tissue contains about 87% lipids, so that 1 kg of body-fat tissue has roughly the caloric energy of 870 g of pure fat, or 7800 kcal."
- just put that quote into google and it will show up on a dozen sites - but no primary source for it. - still that conveniently gets to the well cited 3500kcal/lb of (human) fat.
The closest i have to a real source for such info is
Higher Up and Further In
if you're intersted in going deeper into the physiology here, may i recommend
Exercise Physiology: Energy, Nutrition, and Human Performance, 6th Ed.
McArdle, Katch & Katch (US| UK)
There's a 7th ed coming in November 09.
If you get really intrigued, for after the above, there's Brook's bioenergetics, referenced in the side bar book recommendations
Related Posts
In fact, fat is our biggest and one might argue most versatile sources of fuel. It also makes up the shell of every cell in our body, and is part of a host of other essential for life processes that happen inside us. But the focus of this post is on how fat contributes to providing us with the fuel we need and use in every breath we take.
Fat is amazing. It's the most abundant fuel source in the
body.Every time we breath we're using fat to help take care of the energy needs of our bodies, whether thats muscular activity of lifting something, or the chemical activity of digesting something, or the transport activity of moving something from one cell to another.
In each of these cases, Fat contributes the lion's share of the energy to our physical processes. We couldn't live without it: adipose tissue affords protection to our body's various systems as well as immediate fuel storage sources; the membranes of cells are part fat and enable standard operations of the heart and lungs to get nutrients throughout our systems. And, it's also an energy reserve. Like having a bunch of batteries in the cupboard ready for when the smoke alarm or flashlight fails. Swap out the old cells put in the new.
Despite these great capacities, most of us want to shed some extra weight. Indeed, we know that it's our incredible ability to store fuel resources that works to our socio-cultural detriment in a society where fuel-as-food is readily and cheaply abundant. We put on extra weight. We carry reserves in excess of what we need given the ready abundance of fuel around us. And there are some pretty nasty health costs to carrying around that much surplus fuel, too. Type II diebetes, metabolic syndrome, additional load on joints, etc.
And so we look for ways to burn it off.
The goal of this article is to take a 50thousand foot view (ie really simplified view) at part of what's going on with that burn off, and why therefore fat is our super fuel and seemingly super nemesis.
What i mean by simplified view? Here's a map of the metabolic process:
A metabolic map, indicating the reactions of intermediary metabolism and the enzymes that catalyze them. Over 500 different chemical intermediates, or metabolites, and a greater number of enzymes are represented here. ((c) 1997 20th edition, designed by and courtesy of D. E. Nicholson, We're considering a wee fraction of this entire process, and only part of what's going on as illustrated below (source):
The three stages of catabolism. Stage I: Proteins, polysaccharides, and lipids are broken down into their component building blocks, which are relatively few in number. Stage II: The various building blocks are degraded into the common product, the acetyl groups of acetyl-CoA. Stage III: Catabolism converges to three principal end products: water, carbon dioxide, and ammoniaThese maps help to get that this is complex cool stuff. we are amazing. The above maps let us ask the question - how do we get the good stuff out of fat to use? and to appreciate how a little bit of fat goes a really really long way. To get to that, we need to consider what energy from fat means. And that means taking a look at ATP, the primal fuel block (what fat and other nutrients in large part become), and also situating fat a bit relative to other nutrients like carbs and protein in this fuel-making process (nothing shines out like a comparison). We'll take a wee look at what can increase the fat burn in cells (mitochondria) and finally, where this should lead: why fat, while it burns all the time, is still a challenge to shed.
Energy from Fat
Anyone who's spent time counting calories likely knows that the standard wisdom about calories is that carbs are 4kcal per gram and so is protein. Fat however is 9kcal per gram. Remember a calorie is a measurement of energy: the amount of energy to raise 1 g of water 1 degree.
Right from the outset, it looks like fat has the advantage in providing us with more energy than either carbs or protein. Looks like about twice as much. That's true. But what is really cool about fat is that it gives us more useable fuel for the body to do its lifting, chemical processing and transporting than we get from protein or carbs, and that's in terms of it's translation from a fat to ATP.
ATP
ATP or adenosine triphosphate. ATP is what powers all the energy in cells.
We hear a lot about ATP in the body building world and general strength training: in big lifts the point of that long recovery is to replenish phosphocreatine stores that can make a little bit of ATP available without the presence of oxygen - like when we hold our breath, or exhale out, to do that big dead lift, or keep our head under water for that 50m sprint to the end of the pool. 1 molecule of phosophocreatine when it's broken down into ATP yields only a few ATP molecules. That's not a lot for intense work, but it can re-synthesize quickly for short 30sec bursts.
But what about for efforts that last longer than 30secs? Then we start getting into carb and fat world. Protein is used for very little energy - 2-5% - it has other jobs. If no other source of fuel is available for energy - no carbs say after a workout and you use protein - a chunk of that protein will be used as fuel - transformed into carb-like fuel for replenishing energy stores. And when folks take on more protein than can be used for any current physical requirements, protein will be translated into fat.
Digression on Protein and Starvation
Here's the other thing about Protein as fuel: some folks find that when they're working out and dieting at the same time, it seems their fat loss stalls out. That's a well-studied phenomena that if the body has fat for fuel, and it feels like it's being starved (only recieving 50% or more of the needed cals for maintenance), it will horde fat for as long as possible, and will start to catabolize (break down) other sources in our bodies for fuel. Protein from muscle is a goody.
So often folks starting an exercise program after they've started dieting need to INCREASE their calories a bit to off set starvation.
Now if someone persists at starvation levels long enough, the weight will come off. The famous Minnesota experiment demonstrated this action.
So back to ATP - and ATP from our nutrients.
The body stores only 80-100g of ATP at a time. So it has to synthesize ATP all the time.
A huge point of taking in food is to convert these fuels into ATP. Without going into the detail here, here's where fat comes into its own: a molecule of glucose (stuff from carbs generally), depending on the source, produces 36 or 38 molecules of ATP. 1 fatty acid molecule (derived from fat sources) produces 460 molecules of ATP. That's considerably more than 10 times the amount of usable fuel for muscular, chemical and transport activities than carbs.
Why is this? Basically the way fat breaks down more of it can be translated into ATP than carbs. If you look at the second big map above, you'll see that carbs have to go through three intermediate steps before they get to acetlyCoA. Fat can go pretty much directly to that stage.
Fewer steps, less stuff used for other things than ATP...
The process of how these various translations of a food into a bundle of energy occurs is really cool. It's a testament to how adaptable we are. For instance if we don't have enough carbs in our bodies for the jobs carbs are used to do - like feed our brains and liver - the body will translate fat into carb substitute. This process is the subject of books like Lyle McDonald's excellent review called the Ketogenic Diet.
Why bother with carbs at all if Fat is so awesome? and is that the secret of these "low carb" diets?
Fat burns in the flame of carbohydrate.
One of the best ways to stoke fat to burn is in the presence of carbs - this has to do with stuff in the Citric Acid Cycle. When carbs aren't present and the body has to go ketogenic to use fats instead, well, it can do it, but it's not necessarily optimal. You can skip this next bit if you wish but some folks have asked for a bit more explanation of what this Flame means. So the following digression:
Always on, All the time - when possibleAnd just a note: that even diets that cut out grains and other what we might call fast carbs (fast to become avilable as fuel) to go ketogenic, even here one is encouraged to eat veggies. Lots of them. Why? carbs are part of our natural metabolic process. A third of our energy comes from carbs. Our brains like carbs. Our fat burning engine likes carbs; our muscles like carbs. In balance.
remember that all our energy systems are in play pretty much all the time. There's a little bit of glycolysis (carb burning) happening along with beta-oxidation (fat burning) even when we're at rest.
a by-product of the whole carb burning process is oxaloacetate (OOA). It connects with Acetyl-CoA to form citrate, and that gets processed in the citric acid cycle and ATP is produced.
Duel types of fat
Now here's the cool thing. Fat is so versatile it can get used as fuel a couple of ways. One of these - that produces the MOST ATP is via getting it into the citric acid cycle (see diagram above). This is what FFA's - free fatty acids do. Fat also becomes available as fuel as Glycerol. When you're low on carbs, it's glycerol that gets used as carbs (via gluconeogenisis) - whether you're doing a heavy workout or doing a ketogenic diet. BUT a molecule of glycerol only produces 19 ATP molecules.
FFA's Rock
Compare this rate of ATP availability with what FFA's do when they can enter the krebs cycle. Without getting into the Krebs cycle, fat conversion is also a relatively slow process so that pathway won't get energy to the muscles super quick. Which partially explains why even if you're on a ketogenic diet, most folks recommend getting some carbs into your system prior to a workout in particular for better available energy - and fat utilization. Now this is not to say that we don't adapt in a ketogenic situation to get the turnover of fat into carb substitute happening faster, and when loads are reasonable, all could feel ok. But even so, that rate can't compete with FFA going through the citric acid cycle.
Fuel from FFA is FFA going into Citric Acid Cycle (burning in the flame of carb)
first step is beta-oxidation of a FFA: cleaving off a couple of carbons from the fat (see first image by the battery) and we get products NADH and FADH2 which can form up into acetylCoA which can hook up with OOA to do the citric acid dance. This cycle in turn breaks down the acetylCoA into co2 and H. The H come out of the citric acid cycle to oxidize via something called phosphorylation. The result is 460 ATP from FFA conversion to energy.
SO this is why fat burns and really BURNS up in the flame of carbohydrate.
And fat in something called "slow glycolosis" (part of the Krebs Cycle, pictured as the ring in the second figure above) loves carbs to let it burn baby burn. Now before anyone jumps on me, no Fat does not REQUIRE carbs to help it break down into the stuff that enters the KC to become ATP but it is sort of the path of least resistance, perhaps, if i can put it that way.
And just to repeat what may well be obvious to all:
fat burns as fuel via the happily fairly constant activity of breathing. Fat is "oxidized" to break
down into fuel. This oxidation takes place in the mitochondria of the cell. Hence it's important to have rather a lot of it as we breath so much.Aside: Fat Burners. We may also recall that the discussion last week about super intense low volume 6min. workouts a week created as many new mitochondrias (ie fat burners) as did 1-2 hours a week of steady state cardio. Want to enhance fat burning? combined with diet, enhancing mitochondira helps.
I dunno, just thinking about all the things a bit of fat does it once again strikes me how incredibly amazing we are. So versatile. We can fuel ourselves up with just about anything we ingest. Our systems have preferences but can adapt to circumstances. Wild.
And fat is wild because it does so much for us.
Losing/Burning Fat - Hard Homeostatic or Hard Habit?
But you may be asking if we're burning fat (converting it into ATP pretty much constantly), why are we Fat? Why is fat hard to lose?
I guess the question might be reframed as is fat hard to lose?
What is hard, it seems, when food is so easily available to us, in ways historically unprecedented, we follow our ancient wiring and we eat. We want to load up for the lean times. But we don't live in scarcity. Access to ready prepared food continues to increase. Our need for these responses to horde up are less appropriate.
see
Hays NP and Roberts SB. Aspects of Eating Behaviors "Disinhibition" and "Restraint" Are Related to Weight Gain and BMI in Women. Obesity 2008:16, 52–58. doi:10.1038/oby.2007.12.
So perhaps what's hard is the habits around caloric restriction: being patient enough with ourselves to learn new habits to support some caloric restriction to lose weight. To be patient with ourselves that fat loss takes time. While the inital excess fat may come off faster, those last ten pounds are killers, and there are reasons for this too that i've discussed elsewhere.
And without habits to support ongoing lean attitudes, then how do we keep the weight coming off? and then how do we maintain our goal weight?
I've said it before, its this need for habits around food rather than specific diets that i like precision nutrition. It supports habits.
Rewiring for Fat: Love your Fat; Burn your Fat; Respect the Fat
So while we are wired to grab store and horde fuel, we can adapt our behaviours to be lean in the face of abundance. Once we start turning on those habits, we do need to tune them to optimize fat burning. The basic part of fat burning is to get the balance of eat less right with whatever activity one is at, so one stays productively above starvation level.
Being patient with ourselves to learn what that sweet spot mix of caloric restriction and workout effort to optimize fat burning - if that's the priority - takes time, patience, and a strategy to be able to assess if what's being tried works. Again, i'll say i like precision nutrition becuase it has a method called an Individualization Guide to support exactly that process.
Calorie Note: Why only 3500kcals to drop a Pound of Fat?
Some folks have noticed a seeming discrepancy between cals in a pound of fat and that there are fewer calories to burn a pound of "fat"
I'm still looking for sources on this, but here's the argument: let's start with the basics.
1g of fat = 9kcal
so 1kg of fat =9000kcal
9000/2.2 = 4091kcal / pound of fat (1kg/2.2=1lb)
Apparently a pound of human fat is made up of 10% water + 5% other materials that aren't digested - i need sources to support this, but if we go with that for a moment
4091 -15%= 3477.35
That's approx 3500kcals.
One other frequently quoted statement on the web is "Human fat tissue contains about 87% lipids, so that 1 kg of body-fat tissue has roughly the caloric energy of 870 g of pure fat, or 7800 kcal."
- just put that quote into google and it will show up on a dozen sites - but no primary source for it. - still that conveniently gets to the well cited 3500kcal/lb of (human) fat.
The closest i have to a real source for such info is
Adipose tissue contains 82-88% fat, 2-2.6% protein, and 10-14% water. The energy yield of adipose tissue is 8000-9000 kcal (34-38 MJ) per kg or 3600-4000 kcal (15.1-16.8 MJ) per pound.and that's at Answers.com, and i've no idea who writes this stuff for them or from where they get it.
Higher Up and Further In
if you're intersted in going deeper into the physiology here, may i recommend
Exercise Physiology: Energy, Nutrition, and Human Performance, 6th Ed.
McArdle, Katch & Katch (US| UK)
There's a 7th ed coming in November 09.
If you get really intrigued, for after the above, there's Brook's bioenergetics, referenced in the side bar book recommendations
Related Posts
- getting off diets and onto better eating habits. change is pain: reduce the pain :)
- becoming a better burner: 6mins a week to trigger mitochondrial growth = to 4.5 hours cardio
- cardio with kettlebells
- vo2max effort training
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