Monday, July 21, 2008

Review of the "Science" claims of the Warrior Diet

The following is offered as a work-in-progress investigation of the science claims about the Warrior Diet - both claims about how it works and why it is postulated as a better than the alternatives. The critique is restricted to those claims that are supposedly based on "science" and are listed on the Science page and critique of other diets page on the WD web site.

This post is what some would consider long. That's because there's a lot of material to cover. If you want to cut to the chase, however, just scroll down to the Summary section towards the end of the post.

My motivation for this investigation is so many RKC colleagues whom i respect recommend this diet often. When i first started looking at the description of the diet and its rationale, the descriptions jarred with what i had been learning about nutrition, and so i sought out health and nutrition experts for their insights.

I would also say that, as any scientist or researcher would, there's a lot we don't know about the how's and why's of the way we work. If this diet works for some folks, that super. I pick no bones with that. My concern is that the rationale ascribed to why it works seems problematic.

I freely admit i am a rationalist for matters physical. While i am also a critic of scientific positivism, i do find that science provides some pretty effective means for getting at how things work. For instance, while presidential candidates for the republican party were asked this past year if they "believe" in evolution, i will say no, i do not "believe" in a theory, but as a theory it's got a lot of good evidence to back it up. A heck of a lot more than the alternative.

Over the past year i have been investigating the science of nutrition, in so far as my non-chemist eyes can explore it. To that end, based on a post by David Whitely, a respected Sr. RKC, pointing to John Berardi's precision nutrition, i investigated that program (after looking at a host of others) and thought, yes, this approach has the most complete goods. Indeed, the folks who regularly chat on the PN forums are scientists in the field, practitioners, registered dietitians, graduate students in kinesiology and related practice, as well as trainers. In other words, folks who know this stuff and work with athletes and regular folks on a regular, rigorous basis.

Now, while i personally practice the Precision Nutrition habits approach to nutrition, i'm also very much attracted to kettlebells (KB's), and how the work with KB's has been described by Pavel Tsatsouline. Over at the main meeting ground of practitioners of this style of KB is a nutrition forum. Another name for it could be the Mostly about the Warrior Diet forum. In his books, and occasionally online, Pavel explicitly states that this is the diet he likes and follows, while also stating that he's not a nutrition expert, but that it works for him. So with a source like that to point the direction, why not check it out?

Before encountering Pavel, however, i encountered Clarence Bass of Lean for Life and the best looking 70+ year old on the planet (next to sean connery, of course). And Bass's reasoned assessment of the Warrior Diet was a little less accepting, in particular on the point of training on empty.
Hofmekler couches his diet in terms of "natural wisdom" and the instinctive eating cycle of the ancient warrior. He also includes the concepts of freedom -- to eat as much as you want in one large meal (as long as you follow the Warrior Diet rules) -- and spirituality. "Many people have long believed that one can only experience a deep spiritual awareness when fasting," Ori writes.

I don’t quite see it that way, however. In my view, the Warrior Diet is basically an extension of the concept of training on empty. Ori says controlled fasting 16-18 hours a day "guarantees hours of fat burning." (See our FAQ page for a discussion of training on empty; I don’t buy it.)

Hunger, says Hofmekler, "triggers the Warrior Instinct." It makes you "sharper, more alert, more energetic, and more adventurous." Still, if you must, he says it’s okay to have some "live" raw fruits or vegetables, and even a small portion of protein during the "undereating phase." (For my review of the research on fasting, see "Fasting" and "Starve & Get Fat" in chapter 7 of The Lean Advantage 2." Most authorities agree: Fasting is generally a bad idea.)
While Bass's review was written in 2001, current research still largely supports Bass's assessment. It's this: that training fasted does have draw backs especially for recovery post training. While some positive effects of fasting have been found, none of them are the soul domain of fasting. All of them can be supported with good nutrition and exercise. In other words, one doesn't need to go hungry to live well and thrive.

The Terms and Claims about the WD: sources used
If the research shows that fasting is not necessary to achieve a host of good things for health, what are the claims of the WD?

It's important to note that Hofmekler's WD text make it hard to see how claims about how food is processed by the body are backed up since there are no direct references to any particular research or text books. When i raised this point in a discussion, a colleague pointed me to another book by the Hofmekler called Maximum Muscle Minimum Fat: The Secret Science behind Physical Transformation (MMMF for short) that was supposed to provide the science behind WD claims. In MMMF, there are indeed a number of books and articles listed at the back of the volume, but none are referenced within the chapters of the book, so it's not possible to unpack which references Hofmekler sees as supporting which claims.

This non-citation /bibliography-only approach is pretty unusual. Take for instance a diet book like Lyle MacDonald's the Ketogenic Diet(here's a post about his approach to nutrition). Every second line, it seems, has a reference to the article or text used to support the claim being made: what claim goes with which article is clearly indicated. That's basic practice so a reader can see for themselves how the author is building their case. That doesn't happen here. All the more reason i've been grateful to be able to connect with experts in physiology, nutrition, recovery and training to understand these claims.

In investigating this question of claims about the Warrior Diet, therefore, i've turned to the main document Ori Hofmekler, the author of the WD presents to the world about the "science" on the Warrior Diet. These are the science page of the WD site, and the page comparing WD to other diets. These are promotional pages to encourage people to buy the book, so the veracity of their claims is important. I also reference the Warrior Diet book to clarify key WD terms like "undereating," "overeating" and "controlled fast." So, let's start with the concepts, to make sure we're all on the same page, and then go to the "science" claims.

Controlled Fast vs Intermittent Fasting or any other Kind of Fasting
A theme in the WD is fasting. It's discussed a lot, from its alleged religious to physical properties. That would make one think that a good part of the WD is about fasting. Indeed, the "controlled fast" is a key concept in the book. So what is a controlled fast and how is it different from the popular mot du jour "intermittent fasting" or "caloric restriction."

In the IF literature, intermittent fasting is actually NOT eating for a fixed period of time - either within a day or of whole days. As the IF101 site describes:
* Daily Fasting: Typically done every day and only giving the person a smaller eating window in which to get their calories. (for example, a 18hr daily fast would mean someone would only eat every day between the hours of Noon and 6pm). You will see varying times from 15-19 hours for daily fasting.
* Fasting 1-3x a week: This could also be called alternate day fasting/calorie restriction (for those doing it every other day). This is just fasting of usually longer periods 18-24 hours but only 1-3x a week. Many variations to play with here.
Caloric restriction, it should be noted, is a far more liberal definition: as defined in an overview of IF related research by the Journal of the American Medical Association, it's anything less than "ad libidum" - or less than eating what you want, as much of it you want, whenever you want

Controlled Fast, Part II: Undereating, Overeating
So where does a controlled fast fit into these points along the eating spectrum of Fasting (no food at all for a given period) on one end and ad libidum on the other?

It's hard to say, explicitly; we need to infer a definition from the WD text. Here's why: Part one is labelled "controlled fasting" but it begins with a discussion of "undereating" as an alternative to fasting which is too extreme, he asserts for most people.
Moreover i believe the best way of going through the Undereating Phase is by following a controlled fast, not a water fast. Controlled fasting is easier to follow and it accelerated detoxification and overall well-being.

This is as close to a definition of controlled fasting we get in the book. Immediately after this, 2e get lots about the alleged benefits of controlled fasting, but nothing specific about what this means. We get instead a discussion of what happens in the body supposedly when we fast, and a whole lot about fear of hunger and various other suppositions about the role of fasting in history. The closest we get to an explicit statement is on p27 in the section "If you find it difficult to adapt." Suggestion 1 is titled "Gradually increase the controlled fasting time" in which readers are told "Start by undereating from morning until noon, and then add an hour or two per day."

Ok, so, effectively we have two terms for the same thing: controlled fasting = undereating. It would seem, therefore, that despite all the preparatory discussion about fasting, controlled fasting is not fasting in the IF sense (going without any food for a given period), but simply eating less, or what Hofmekler calls "undereating." Indeed Hofmekler writes, "On the WD the principle of fasting is based on not eating a full meal during the day"

Intriguingly, the non-full meal during the day is defined as consuming raw vegetables or vegetable juice "with some portion of protein, if needed." Hofmekler is down on protein during the day as it allegedly interfers with letting the body detoxify and "rest." To minimize this "stress" Hofmekler recommends cottage cheese and lean animal protein or almonds instead (p33). In the WD, Cottage cheese, some fresh veg and fruit, a glass of juice is undereating. For many of my colleagues, this mix of protein and carbs (and the fat also contained in say the cottage cheese) constitutes a "full" meal. But if it is not a full meal in the WD sense, what is?

The full meal is presented (implicitly) in the "overeating" phase - or Feast. It differs from the undereating meal as far as i can tell in one way: it adds what it calls "carbs" to the meal.

ASIDE This is another curiosity in the WD: veggies are separated out from "carbs." In the WD only the more starchy carbs like rice and pasta are labelled as carbs, whereas veggies are called "vegetables." But vegetables are a key source of carbohydrates.

Hofmekler in describing the "overeating" makes a number of claims about the order of eating during the Feast meal: start with veggies, then eat protein, then if you're not satisfied, eat what he defines as carbs.

Hofmekler makes a series of unsupported or careless claims about these "carbs" when eaten in a feast (that is, with protein and fat sources) (p82)
1) carbs "create satiety since they naturally boost serotonin production in your brain."

There seem to be two problems with this assertion:
(1) Only starchy/sweet carbs increase serotonin levels (2) they don't produce any serotonin when ingested with protein (ie, at a feast).

2) "we don't want to boost too much insulin" Hofmekler asserts, and so claims that when ingested with protein and veg, "the glycemic index of any carb that is consumed afterwards is automatically reduced"

First, a technical point, but the GI of a food is the GI of a food; it doesn't change. Second, the rate of digestion of starchy carbs when combined with other nutrients doesn't slow down their rapid availability to the body. This is why nutrient timing approaches (eg, Precision Nutrition, overviewed in this doc) recommend eating starchy carbs in meals that come after workouts, when the body is most sensitive to insulin, and muscle glycogen stores have been reduced by a workout. In this state, the body can best take advantage of the more rapid availability of the glucose available from these starchy carbs for replenishing that depleted muscle glycogen. The factor that facilitates this uptake is the insulin triggered by the presence of the rapid abundance of sugars from these fast digested sources.

If we therefore feel satiety and "relaxed" at the end of a big meal, it's not serotonin; it's the demands of the body to shunt blood to the GI away from our limbs to process food. The full warrior is a fleet warrior?

So, while Hofmekler advocates eating what amounts to a whole food diet, he adds a variety of provisos, like eat less during the day; more in the so called "full meal" in the evening; eat the foods in a particular order, etc etc. The motivating question is, what's the basis for these prescriptions around what to eat when?

In the absence of Hofmekler's connecting the dots of research sources to his claims either in the WD or his Maximize Muscle book, i've sought the council of experts in diet to help understand what's being claimed. Here's how the discussion has gone. Again, for this part of the discussion, i'm pointing to material available on the WD web site so it's available to any reader.

Fast to Feast to Fast Metabolism
The first claim on the Science page is that eating a single BIG meal a day will speed up the metabolism.
[W]hen people practice overeating after undereating, their body changes to a more thermogenic and highly metabolized state. The brain receives a signal that it should elevate metabolism in order to burn the extra energy coming from food. On the whole, when one overeats after a controlled fast, nutrients are assimilated at a greater rate, there is an acceleration of the anabolic process of repairing tissues and building muscles, depleted glycogen reserves and intramuscular triglycerides (special high octane fat fuel in the muscle) are replenished, there's an increased secretion of dophamine, thyroid hormones, and an elevation of sex hormones. If overeating is practiced regularly, your body's metabolism will remember this, and while adapting to these daily big meals, it would most likely become metabolically faster and more efficient than before.

A sped up metabolism is a good thing for folks wanting to lose weight because all a fast metabolism means is that we are needing more energy to support the body's activities [metabolism explanation 1, metabolism explanation 2]. That energy comes from fuel - or the food we eat or the energy we have stored as fat (and the sugars we have in our muscles).

There are a bunch of claims in this section of the WD site about metabolism, so let's take them one at a time:
when people practice overeating after undereating, their body changes to a more thermogenic and highly metabolized state. The brain receives a signal that it should elevate metabolism in order to burn the extra energy coming from food.

Okay, food of any kind has a thermogenic effect because it takes energy to break it down (see Power of Food section). Some foods take more energy to break down than others. Protein takes more energy than carbs, for instance. So, actually, eating more frequently keeps your body's metabolism revving over a longer period of time, because each time you eat, especially if you eat whole foods, you're using goodly amounts of energy to consume it. So the argument for overeating meaning higher thermogenic value doesn't quite fly there. Let's move on.

On the whole, when one overeats after a controlled fast, nutrients are assimilated at a greater rate, there is an acceleration of the anabolic process of repairing tissues and building muscles, depleted glycogen reserves and intramuscular triglycerides (special high octane fat fuel in the muscle) are replenished, there's an increased secretion of dophamine, thyroid hormones, and an elevation of sex hormones.

Wow this sounds good: after starving, when you eat, you get more benefit - better nutrient uptake; better muscle building; more hormones, more more more. But more and better than what? According to what research?

On the other hand, i can point to considerable work that shows that frequent feedings do in fact have tremendous benefit for hormone levels, metabolic rate and tissue repair. Here's one example by Benardot at Georgia State University that has shown that increased feeding frequency (5 meals vs. 2 meals) at the same daily caloric load, improves Lean Body Mass (LBM), decrease Fat Mass (FM), *increases resting metabolic rate,* better controls blood sugar and insulin, decreases blood triglycerides and more (download a pdf on this research).

So the claim about the benefits of fast/feast really haven't been met here based on accepted science. Indeed, at least as far as i could find, the counter arguments seem to hold. What we get to, ultimately, is an assertion not of fact but of of Hofmekler's "belief" in a particular approach:

Scientific studies indicate that there's a correlation between our metabolism and how many calories are consumed per day. However, as far as I know, no studies have been conducted on the correlation between our metabolism and the amount of calories consumed per meal. I truly believe that the amount of calories consumed per meal is the bottom line.
Actually, there's a lot of research about amount and kind of food consumed per meal, like Bernadot's above, and the various papers cited in it, as well as comparisons between ad libidum feeding and fasting, as overviewed in the JAMA article. There's also considerable experience with what's known as calorie and carbohydrate cycling for both fat loss and lean mass gains.

What is well know and accepted science is that caloric restriction slows down the metabolism; it does not speed it up. In particular, with respect to Hofmekler's claims about a big meal speeding up the metabolism again after undereating, the contrary seems to be indicated, as stated by Registered Dietician (difference btwn RD and Nutritionists) and PhD student G. Fear, "[a]fter underfeeding, your body is primed to store incoming calories as fat, not to ramp up metabolism to burn them."

Some may say "malarky: i've been following the warrior diet and i'm losing weight." Bottom line, if you've cut out crap, are eating less during the day and one sit down meal at night, and are losing weight, at one level you're just taking in fewer calories. And it really doesn't matter what approach you use: if your input is less than your output (the fuel you need for burning), you lose weight. Your loss gains may be improving as well because you're working out more, which also means more fuel demand from adaptation of various systems etc. So, if you're losing weight it may not be down to any particular magic about undereat/overeat, but in cleaning up input and having reduced caloric input vs the same or greater caloric demand.

It's also interesting to note that in what is termed the "science" page for the WD site, the basis for the author's assertions about his approach get down to belief about how his system works. In science, sometimes such a belief is couched as an hypothesis: a claim to be tested. How have Hofmekler's claims/beliefs been tested? Let's hold that one, too, and move onto another assertion.

More on Metabolic Acceleration
Let me give you an example of how adaptation works. People can walk for two hours every day without noticing any improvement in muscle, strength or speed, but if they sprint for only five minutes a day, they will most likely notice improvement in both strength and speed . So, it's not necessarily the length of time spent exercising, it's the intensity of the exercise. Coming back to the subject of diet, the question remains: Is it the intensity of the meal that will dictate your body's metabolism? My answer is yes. That's the way I experience it.
The above represents an effort to create an analogy to suggest how one thing works can be used as a model of how another thing works. Teaching by analogy is part of a great pedagogic tradition. But the first question in designing the analogy would be to test if the analogy itself is accurate for the point being made?

The assertion that people can walk for hours a day and notice no difference is absolutely false. The research done, for instance (and this is just an example) with de-conditioned or elderly populations getting them into Mall Walking has made significantly measurable improvements in their cardiac health and reported weight loss progress. Recent research showed in fact - from a large sample population - that inability to walk a 1/4 mile a day (what a very slow person could do in 15 -20 mins) is a predictor of mortality and poor health in the elderly. Greater benefits have been shown *potentially* in elderly populations that mixed their regular walking pace with some bouts of more intense walking ( i don't have the details on how "intensity" or duration of interval was measured or set, but it's still walking, not running).

To continue with the analogy, with respect to sprinting for FIVE MINUTES EVERY DAY and the contention that someone would notice improvements in strength and speed, let's check that out. What's a sprint? It's an all out effort for either time or distance. For folks in the kettlebell or crossfit space, that may also be equivalent to doing the Tactical Strength Challenge Snatch test - all out numbers with a kettlebell in five minutes. Now imagine being asked to do that *every day.* In Pavel Tsatsouline's Enter the Kettlebell, the bible of kettlebell initiation (review here), Tsatsouline says to practice one's snatch only once a week.

Likewise, when training elite athlete sprinters, they may only be asked to sprint - actually sprint - once or twice a week because it's so taxing on the system. That is, the body needs the rest of the time to recover from that effort. If doing that every day with an elite athlete would be at best damaging, imagine what that would be like for our unconditioned or elderly population?

In other words, far from the author's contention that this sprinting approach would lead to strength and speed gains, repeated practice and research demonstrates that the results would be the exact opposite of what the author suggests. So if the Warrior Diet is indeed like (trying to) sprint every day, then it would be seen as both unsafe and therefore a poor recommendation on those grounds alone.

Next Claim - Overeating is a deep instinct

The Warrior Diet is the only diet that explores the advantages of overeating. Let me say something to all those who overeat and then feel guilty. You feel guilty because you didn't know that a deep, primal instinct drove you to overeat. An instinct that we have most likely inherited from our late Paleolithic ancestors who were night eaters, cycling between periods of famine and feast (undereating and overeating). Many people binge late at night when exhausted from a rigid, obsessive, daily self-control. That's usually the time when inhibitions are broken down and the alleged "demons" come out. But these are not demons. If you know how to use this instinct in the right way, it can work for you instead of against you.
I'm not sure where the author gets the evidence to suggest that our Paleolithic ancestors were "night eaters" or that this is a good model, or not. Let's face it: how would we know? The only remains that will keep over a long period of time are bone and, if you're really lucky, seeds (my undergrad summers were spent on prehistoric sites - believe me i've catalogued enough fish otoliths to have a sense of this - but don't take my word for it: check in with archaeologists who look at diet (paleo diet critique 1; journal special issue 2)). Anything therefore about our long long dead ancestors is largely speculation (that's anthropology) on thin evidence. To be able to claim with any certainty we ate at night is in that light, rather astounding.

So who likes to binge at night? Perhaps folks who grab a quick cup of Joe and something sticky as they run out the door; sit at their desk, maybe grab a sandwich of dubious quality and don't eat anything else till they get home. No kidding they're hungry. Not sure who would argue, howerver, that that approach to eating is a sign of warrior like organization, preparedness and practice. Most of us would call that rather the approach of the couch potato, who far from being svelt is over weight.

Frequent Feedings vs The One Big One
We now hit what seems to be the key rationale behind Hofmekler's approach to eating: rest. On a comparison with other diets page, Hofmekler says that really, frequent feedings are just too hard on the system - it never gets a chance to rest and detoxify, and that just stresses the pancreas and is a fast track to GI distress, whereas the warrior diet is about "daily detoxification and enzyme loading" Here's the quote:

The frequent-feeding system (followed by many people today) is where you eat relatively small, frequent meals throughout the day. Those who advocate frequent feedings say that it puts less pressure on the digestive tract, allegedly keeps sugar levels stable. And, especially for physically active individuals, it allegedly enables them to ingest more protein throughout the day to further build muscles.
Well, hmm. The assertions about the rationale for frequent feedings are without reference. The system of frequent feedings with which i'm familiar, Precision Nutrition, makes no such claims as those asserted in that first paragraph. You can either check out the rationale for the approach at the PN site or read literature like Bernadot's, cited above, that looks at nutrient timing relative to what we know about optimizing resources to our bodies when they need it, throughout the day.
So, setting aside that point, let us consider the rest of Hofmekler's claim is that
The huge disadvantage with the frequent feeding system is that your body never gets a break to detoxify, to recuperate, and to let the pancreatic system rest. Additionally, when you deposit material so often, without giving your body enough time to detoxify, you basically deplete your body's pool of enzymes. This often results in compromised digestion - especially of proteins. Indigestion weakens the immune system, and if this goes unchecked, leads to disease
A large percentage of those who practice frequent-feeding no longer have a healthy feeding cycle. It's no wonder why so many today suffer from digestive disorders, constipation, weight gain and related diseases. These problems are so pronounced that the companies who sell drugs to help people become "regular" make a bloody fortune.

The Warrior Diet is built on daily detoxification and enzyme loading as key components. If you practice this diet, you'll eventually reach your own natural cycle and should be able to sustain prime health and increase your resilience to stress and disease. This makes the Warrior Diet radically different from all conventional diets today.
If we set aside for a moment the lack of any evidence offered either to define what frequent feeding is in practice, or support that people who follow a frequent feeding regimen suffer any of the ailments Hoflekler ascribes to them, let's focus on the main assertions:

  1. that frequent feeding means the body can't "detoxify" and "recuperate"
  2. frequent feeding means that enzymes are depleted
  3. digestion is compromised
If you look in the scientific literature again, you won't find any papers that show the pancreas being stressed due to frequent feedings. As one of the experts on nutrition of recovery, John Berardi, said, how do you tell if the pancreas is rested and refreshed? His concern was that such a claim - that the pancreas is stressed - cannot readily be tested. So he suggests one needs to frame this as a "falsifiable argument" -

Now, you could likely provide a falsifiable argument - and it would be this -when you frequently feed, you acutely decrease the production of digestive enzymes.

Another would be when you frequently feed over long periods of time, you eventually see a drop-off in production of digestive enzymes in response to feeding.

These can be tested and falsified. Pop over to medline and see if you can find anything on these. If so, then you've got some evidence supporting the Warrior Diet's claims. If not, then you've got no evidence and are on pretty shaky scientific ground
Taking that challenge, i could not find anything that suggested frequent feedings decrease digestive enzymes, or that over time there is a drop off in enzyme production. I did confirm a few things, however, and that's that eating a great big high glycemic meal does have a negative impact on the pancreas. As G. Fear, explains it:

The biggest stress to the pancreas is high glycemic meals, or the large spike in blood sugar following a gorge! Over time, high glycemic loads and the high production of insulin do two things, first they dampen the body's response to insulin (insulin resistance). So the pancreas, already pushing to keep up with your "feasts" now needs to try and make more because the rest of the body isnt listening so well. Thats when you have superhigh insulin levels yet still high blood sugar (the first stage in type 2 diabetes). Eventually, the pancreas wears out and insulin drops off to virtually nothing, which doesn't matter much because the insulin doesnt work anymore anyway, because the body is too resistant. (Thats why type two diabetics dont get insulin shots, it wouldnt help them like a type 1).
This is not to say that folks on the WD eat high glycemic meals when they feast - i just point this out as the one core research related, scientifically supported issues around the pancreas being pushed beyond capacity: it's not frequency of meals; it's regular, high GI input. I now have a better understanding of the causes of Type II diabetes, but no proof that digestive enzymes fall off, or that the pancreas is any more stressed or not with frequency of feedings. I only have examples of research as cited earlier that show the overall benefits. To the particular claims about frequent feedings causing us to deplete the "pool o enzymes," Fear states that little could be further from the case:

First, your body does not run out of digestive enzymes. You have way more enzymatic capability than the amount of food you could possibly consume. Studies have been done to see just how much people could absorb, and the subjects were still absorbing fat at virtually 100% when they were force fed 500 g of fat a day. Your body is very efficient, it has evolved to get every calorie and nutrient out of what you eat and not waste it.

[...] Anyone who says the pancreas can't keep up with multiple meals is not up to date on how the GI tract works [...] the pancreas produces digestive enzymes, but they are stored in the gallbladder until you eat. Its essentially a storage tank, so when you do eat, the gallbladder contracts and squirts the enzymes into your gut. The pancreas is making enzymes all the time and they just get stored until needed. So eating often just makes the galbladder contact more often, but the pancreas is doing its same old job. Eating one big feast a day - gallbladder contracts once, and stores up the rest of the time. Your pancreas will not really have an issue either way.

So, the claim about frequent feedings vs single meals on the pancreas and digestive enzymes also doesn't really bare up under scrutiny of what we know of the science.

When asked about multiple vs a single large meal, Carter Schoffer of Precision Nutrition (a frequent feeding approach to nutrition) stated

Aside from MSG-laden Chinese food, how long after a feast of meal do you stay full? For hours and hours, right? You go to bed stuffed and wake satiated. What's happening here? Well instead of the food waiting in your fridge for it to be consumed, digested and absorbed, it's waiting in your GI tract to be tended to.

How is this any less of a burden to your pancreas? Does it not follow that it's a considerably greater burden to unload a dump truck load of food as opposed to shovel fulls? Is this not seen by (a) how long one remains stuffed (b) how gassy and bloated one becomes after a large meal and (c) how large and unprocessed the stool is?

Your digestive tract is simply overwhelmed - rather than paced along like any good manufacturing/construction process. You don't dump the entire truckload of cement and stones on masons, you cart and trough it to them at a rate they're able to handle, and take advantage of, without feeling overwhelmed.

As I've said countless times before, we eat food for more than just the kcal value. We eat food for overall nutrition. The body does a pretty good job of storing the macronutrients by way of a big belly and bottom and a decent job of storing some vitamins and minerals (in your fat belly and bottom) but it does a poor job of storing a heck of a lot of other nutrients. When you're not eating throughout the day, you're depriving your body of these nutrients and you can't make up for these with a massive bolus of food because your body will have more than it knows what to do with. What follows is a mass exodus of otherwise beneficial nutrients.
Some of the WD practitioners i've spoken with say that they do not pig out in their evening meal - it's size is simply more substantial to what they eat during the day - more "a regular sized meal" - so they mayn't be suffering the extreme GI overload described above, but Schoffer's points are worth consideration.

Intermittent Fasting: Live Long and Prosper - like Mice?
There is one more claim over on the Science page that cites one 2003 study that shows that mice on intermittent fasting had all sorts of benefits from increased longevity to reversal of diabetes. There's only speculation about how this will work, in the long run, for humans.

Why Hofmekler cites this one study of all that work done on IF is a bit of a mystery, since there are studies involving human participants in IF. Likewise, since as we've seen, the WD is not about fasting as understood by any other group using this term: it does not mean avoiding any food input for a period; it means "not eating a full meal." So it's unclear why this study would be seen to support Hofmekler's approach. A skeptic might suggest that this seems like misdirection of some kind.

It's important to note, though, since Hofmekler raises fasting both in the book and on this page of the site, that intriguingly, there is nothing that one can point to that fasting provides in terms of benefit that exercise and good nutrition do not also provide, and without the known down sides of fasting, as this review shows.

Working Out Empty
The last claim i'd like to consider is with respect to claims around working out empty. Again, i know a number of martial artists who prefer this - and that's fine - but they do not make claims that this is either nutritionally optimal, or an approach they would use for heavy training. Hofmekler on the other hand, does make assertions about why this approach is excellent for training and weight loss. In the book Hofmekler states that
post exercise particularly on an empty stomach your insulin receptors are at peak sensitivity...your body is now ready to consume large amounts of food without gaining weight

So, have some protein post workout, he argues.

This is the claim where Bass, quoted at the top of this article, parts company with Hofmekler. Likewise the research on working out in a fasted state (not an empty stomach) highlights the problems with this approach:

Improvements in insulin sensitivity, glucose tolerance (except in women undergoing ADF), bodyweight/bodyfat, blood pressure, blood lipids, and heart rate are commonly cited benefits of IF & CR.

• § All of the above benefits can be achieved by exercise, minus the downsides of fasting.
• § IF and CR have both been found to have neuroprotective effects by increasing BDNF levels.
• § A growing body of research shows that exercise can also increase BDNF, and the degree of effect appears to be intensity-dependent.
• § Based on the limited available data, resistance training performance, especially if its not particularly voluminous, might not be enhanced by preworkout EAA+CHO.
• § Despite equivocal performance effects of pre- or midworkout EAA+CHO, it minimizes muscle damage that occurs from fasted resistance training.
• § Immediate preworkout protein and/or EAA+CHO increases protein synthesis more than fasted resistance training with those substrates ingested immediately postworkout.
• § It’s possible that a partial fast (as short as 4 hours) before resistance training can negatively impact muscle protein status.
Another source to consider is the Fasted Cardio round table for just how far this idea tracks. On the flip side, just because you've worked out does not mean you can eat anything you want without gaining weight. Let's get real. Not all exercises either burn a lot of fuel or tax our muscle reserves of fuel. Does exercise prime you to take on replacement fuel? if at sufficient intensity, yes it does. But does that mean you can eat anything and not gain weight, fasted or not? No. If you consume more than you burn you gain. That's all.

Also, as science about nutrition has shown for eons, "fat burns in the flame of carbohydrates" - there's a long explanation for this all about the krebs cycle, pyruvate and ATP, but bottom line is: with sufficient fuel in the tank, even more work can be done, and more fat burning can take place. Running on empty is sub-obtimal for training. Again, this doesn't mean that people can't train or don't train on empty and feel ok doing it. To claim that it is the optimal way to prime the body to take on fuel, or is an optimal approach to training is not supported by Science.

We can say that science doesn't know everything; science gets stuff wrong. well, alright, then fair is fair: the points made here are that Hofmekler himself appeals to science or pseudo science to back his claims for why his diet not only works, but is superior. The purpose of this article has been to see if those claims either have merit or support - if, indeed, there is any "science" to support Hofmekler's claims *as* science.
Summary: Sans Science
It seems that, taken one at a time, the arguments Hofmekler puts forward on his web site as "science" to assert that One Big Meal a day has many benefits specific to its approach alone is not there. Indeed, as we have seen, some of its claims, such as those about carbohydrates, enzymes, pancreatic stress/rest and detoxification, seem to be problematic at best, if not simply wrong.

But just because the alleged "science" claims about the diet may be wrong, unsubstantiated or confused, does that mean there is anything particularly unsafe or wrong with the diet itself of smaller meals during the day and a large meal at night?

Going back to RD G. Fear, she replies

I wouldnt say its harmful at all to consume all your calories in one big sitting if someone prefers to do that over eating them frequently. I'd consider it optimal for retaining muscle mass and boosting metabolism to eat more often, but if you arent taking in too many calories, you can certainly lose weight that way.

In terms of subjective reports of wellbeing.... its true they could adjust and not feel as hungry. [Assuming that one is NOT eating during the day; is in fact intermittent fasting] being in a fasted state all the time, your blood sugar could be very stable, with the liver meting out glucose [as fuel, rather than getting it from in coming carbs - whether veggies or other -mc ] to keep you going.

Some people have a tendency to get hypoglycemic when they dont eat for long. I think [that is] influenced by 1) consuming a pretty low carb diet 2) eating frequently, so my metabolism is HIGH, 3) eating relatively small meals, so I'm probably not storing up loads of liver glycogen.

Someone who eats more carbs and trains their body to tolerate the daylong fast might feel better... because the liver enzymes which break down glycogen to release blood glucose upregulate. So WD devotees dont "bonk" while waiting for their next meal.
In other words, it's possible to get into a place where the body is comfortable eating one meal a day, and a few folks over at the DD forum have been doing this for awhile. A few. I've encountered more folks, however, who's practice seems at odds with pretty loose relative to the averred approach. I haven't asked them about this directly, so i won't speculate. But i will observe that some long time advocates of the approach at a recent event certainly had a lunch of protein, veg and starchy carbs that would rate as a "full meal" by Hofmekler's definition, and was then followed that evening by what appeared to be an equally adequate full meal dinner. While i said i wouldn't speculate, such an observation might lead one to think that there is something more attractive in the name than in the complete observation of the practice.

In Michael Pollan's In Defense of Food, he writes "who am i to tell you how to eat?"

Likewise, this article is not intended to tell practitioners of the Warrior Diet to give it up. As the summary of the IF review paper states in its conclusion:

It's given that personal goals and individual response are the ultimate navigators of any protocol. Therefore, training and meal schedules should be built upon individual preferences & tolerances, which undoubtedly will differ. However, the purpose of this article is to arm the reader with the facts, so that opinions and anecdotes can be judged accordingly. Personal testimony is invariably biased by the powerful placebo effect of suggestion, and sometimes by ulterior agenda. Science is perched on one end of the epistemological spectrum, and hearsay is on the opposite end. As the evidence clearly indicates, IF is not a bed of roses minus the thorns - there are definite pros and cons.

In the world of fitness, recommendations for improving performance and body composition often gain blind acceptance despite a dearth of objective data. This is common in a field where high hopes and obsessive-compulsive tendencies are united with false appeals and incomplete information. In order to be proven effective beyond the mere power of suggestion, supposed truths must be put through the crucible of science. Drawing conclusions from baseless assumptions is a good way to get nowhere - fast.
Similarly, the purpose of this article has been to set the scientific claims in the context of attributable, researchable science: to ask the question, are the claims described as "science" using scientific descriptions. "science"? As has been shown, those claims are simply not supported by known science.

What we do know to be the case: if we eat more than we burn, we gain weight; if we eat less, we lose weight. This effect is not specific to the WD. Because there are people who do practice the WD and claim to find it beneficial to them, why it works, therefore, is for reasons other than those claimed as science by the author, and which is not. These reasons may range from convenience, psychology or what Mike T Nelson, RKC, calls "metabolic flexibility"

As Kris Aiken, BAHon, CSCS, Precision Nutrition network coordinator suggests however, when asked why a particular diet seems to work, he asks "works compared to what? In terms of not eating at all, it will be better. IMO the body is a very resilient organism and people can often succeed in spite of, and not because of what they do. "

It may well be that the WD is effective because of something rather than in spite of something else; that the method is better than simply being "not harmful," and that it is more than adequate for some people to train as well in a depleted state; that the convenience of eating less, or the sense of spiritual or psychic reward of feeling hungry or of controlling one's self with respect to food intake has a higher reward than on a different plane than providing sufficient fuel to get optimal value from a task. It may also be that we learn new things about the genetic components of food that will offer some insight into this WD approach that we don't have now.

In the meantime, however, the claims cast as science made about how and why it works as cited above are at odds at least with what i've been able to discover about the science underlying what is known about those processes. So if you're doing the WD, and you like it, great - just know that the reasons for why it works for you may not be those that are asserted by its author. Any mistakes in the presentation of this critique are mine, and i'm keen to understand where they might be.

If you would actually like to consider another approach than the WD - perhaps just by way of comparison - maybe explore what frequent feedings or peri-workout nutrition is - there are options: you can check out at least the one example i know of for frequent feedings tested in use from regular folks to elite athletes, and that's precision nutrition. If the thought of managing many meals is one too many, there's also any of Clarence Bass's excellent books on eating whole food. There too, the rationale for the approach is clearly spelled out - and as clearly referenced.

As Michael Pollen writes, eat food, not too much mostly plants. And let me add, eat for fun, love, pleasure - and health.
There's good science in that.

UPDATE Sept 09, thanks to Richard Chignell for passing this along: studies of real IF (like eat stop eat) vs the one big meal (like WD) . Also in the Related Post below on alternatives, i've talked with enough colleagues now who find IF, even weekly 16 hour fasts to be hitting the sweet spot for them.

I've also talked now with a number - not a lot, about a dozen - personal trainers who are in great shape and have told me that they did the WD to burn fat, did, and got mean. I was intrigued by that report. Since they didn't quite care for themselves they changed their approach.

In this recent article on diets and support for successful change in eating practice, i recommend a multi-phased approach. Why not first take the time to get to know - really know - how you and your body react/benefit to different foods under different conditions - and i suggest a few ways to explore that.

Then, once you know about yourself in that regard, play around with whatever style of eating you wish, from ketogenic to IF - just do it with a base of self-understanding, and some strategies to be consistent enough to get through any initial adaptation crises.

Related Posts


Rannoch Donald said...


I need to go back and take some time to read this post properly. I will say this, I can't think of many who take the time to put their thoughts online with such clarity and effort.

I am guilty of simply reacting to what I see and then having a little rant about it. You however take the time to "dig" and that depth blows me away.

No comment til I digest this ('scuse the pun) properly.



Ron Ipock said...

I prognosticate that this will sway no one. People will concede that the WD has no scientific basis but that they love it anyway. It will be like the issue of the death penalty in the United States. Science has shown that there is no reformative nor deterrent quality to this ritual but nonetheless the vast majority still require the blood because someone's gotta pay. It is an entirely emotional argument. WD'ers will be the same way, preferring whatever results they get from their regimen as opposed to the improved results they might get from a more scientific approach

Mike T Nelson said...

Thanks for all the hard work and immense about of time placed in this article! I admire your dedication and determination plus your ability to think for yourself. Kudos!

I had to print it out and give it time for a throughout read threw—good stuff.

A few random comments (many of which you covered)

Fasting and detox always seems to bring up red flags in my mind. The body does an amazing job detoxifying tons of crap (hey, just look at the way most people eat!); but it needs raw materials (proper food) in order to do it. Cutting off all food seems backwards to me.

The body will ALWAYS ADAPT! Even in severe pathological cases like heart failure, the body is still able to adapt (albeit in a non beneficial way at that point), but it is still adapting!

Kris hit it on the head –compared to what? A large meal IS anabolic compared to a fast!

Weight loss vs fat loss—big difference.

I really don’t care too much what people do as long as they have a system in place to measure progress—body fat percentage, strength gains, size changes, body weight, are a few good ones. You may lose weight, but if your muscles get smaller is that a good thing?

I think strength may not be affected as much, but I highly doubt this approach would be good for most trying to increase muscle size (hypertrophy). Again, it depends on the individual as always.

Resting the system---good points. I sure hope my heart does NOT take a rest any time soon.

People need to remember that physiological systems are built up through USE and atrophy (deteriorate) with DISUSE!! This is the direct OPPOSITE of non living systems! If I build a car and stuff it in a vacuum sealed, insert gas filled dark chamber, it will last forever. Put someone on bed rest of chuck them into 0 gravity (space) and they deteriorate at a very a rapid rate! Big differences!

Most need to fix their attitudes about food first. This is a long term process.

Rock on!
Mike N

dr. m.c. said...

Rannoch, thank you for your kind words.

Rip, thank you as always for dropping by. it seems you may be s sooth sayer of some accomplishment.

Alas, my intent was not to sway anyone, since a lot of people seem happy on the main meal + grazing thing, and research is just really fresh showing nutrient timing has an increasing amount going for it. So, beyond the WD prescription to skip processed foods and eat whole foods, do any of the other arguments around meal size, etc, hold water? Does the emperor have any clothes as it were, and if not, then what?

do you know the story about the soldiers and nail soup (a few versions are described here).

After doing this research, it seems to me there's alot of nail here.

Again, gentleman, really appreciate your taking the time to stop by.


dr. m.c. said...

Thanks mike. Just say your note. Appreciate your taking the time to take the time to read and come back on this.

You make a great point that detoxifying actually takes input - real food - to clear the pipes - rather than the lack thereof. Excellent point.

And to blend one more metaphor - you talk about the car. vs how living systems adapt.

Well, i used to ride and maintain motorcycles. My first bike had a cam chain that thwacked around in it something fierce - my neighbor, a bike mechanic said leave it; it's a known issue with the bike and more hassle than it's worth to try to fix.

And then he said something i found to be profound "that bike is a tank: it would keep going on one cylinder." it had four.

now imagine you got a bike that was running on one cylinder - you had no idea it had four, but you did think it could be running better instead of stopping and starting all the time - and you took it into the mystic mechanic who got it running on three, and told you all sorts of things to do to keep it running that way. wow, wouldn't that feel so much better? it's burning gas better, not stalling as much.

you'd send all your friends there

"it's running so much better"

and kris says better than what?

thanks again Mike for engaging on this one.

you rock on yourself, dude.


Georgie Fear, RD, CPT said...

Wow! I never actually read this once it was completed. Congrats on a superior article!! Geez, if I knew I was being quoted I might have been less "casual" in my phrasing, haha. You did a great job of seamlessly putting out all the arguments and posting evidence for each.

"this will sway no one".....perhaps true, just like people who choose to continue to smoke despite the mountain of evidence indicating its dangers. But at least now WDers can't use the "really, science PROVES it!" angle to defend their habits.

dr. m.c. said...

Georgie, thank you both for your contribution and your kind words

re less casual and "if i knew i was being quoted" please check your PN email
from me
Date : 2008-07-09 15:18
Title : wd quotes

and your reply
2008-07-09 15:26 :)

and by the way the replies i've had from WD practitioners have been
a) they didn't read the whole article but that
b) science can't explain everything, and c) wd works.

at the time i felt rather frustrated with that reply.

THanks again for stopping by,

LivingFit365 said...

Thank you very much for such a great post. You've taken the time to actually go through the book and review it properly. The WD is full of so much nonsense. There is some noteworthy statements but for the most part it's faulty.

There is so much pseudo science out there and people writing books based on opinion and theory and their belief system rather than actual fact.

I've just been lurking at the Warror Diet forum:

I was about to join before I bought the book. But after reading your great review I'm not going to get the book now.

Informed, intelligent people like yourself should go onto that forum and correct some of that faulty information. It is pretty much an unmoderated forum it seems.

It may not do any good though, they would still believe what they want to believe. It's like cult in a way.

Thanks again for a GREAT review.

L. Wu said...

For the downsides you mention, unclear scientific backing and so on, there are a few benefits I've gotten for being on the WD for six months or so.

Besides the fat loss (not really a goal, it just happened over the months), I found that it's easier to be spiritual/connected to something greater when you're fasting (as Ori points out). But of course, sometimes angrier too :)

One of the main benefits I've found is that it's a lot easier to be sharper during the day, and as someone who goes into food coma really easily, this was great to be able to work without getting groggy.

Another unexpected benefit is that it's a lot easier to figure out what foods you are intolerant of or allergic to, since you eat one meal instead of 3-5, so the variables are a lot fewer. If something causes you inflammation and you eat a lot of it at dinner, it's a lot easier to figure out! (For me it was cow milk proteins, probably casein...)

I wore a HRM religiously for the first six months of this year whilst on the WD and burned about 60,000 calories over some 100 training sessions. I found that I felt great as long as I didn't burn more than 1500 calories during one 3h practice. At a tournament weekend where I could burn up to 3700 Calories in a day though, about a half-Ironman, I found that I just wasn't eating enough during the day to stay ready..

Nice that you cited Pollan but on a recent trip out to the Bay he mentioned how ""Nutritional science is kind of where surgery was in 1650 -- really interesting, but do you want to participate directly?"

Of course, he was talking more about nutritionism vs eating real food, but the point remains, we still know so very little about how we should eat, and through waves of migration and immigration, so much physical culture and food culture has been lost, reborn, and redefined anew.

That said, I've accidentally dropped too much weight again recently and so maybe when I get back to school next week I'll try out this Precision Nutrition thing that I've heard you and the folks at the podcast talk so much about.

I do wonder though, the creator of PN was on (episode 20?) talking about eating for your body type, and perhaps there's some connection to fasting there? Who knows :)

dr. m.c. said...

Thanks for the comments, L.Wu

And right now, i'm gonna kinda close comments on this post lest it get into a WD good/bad series. That's not the point of the article - despite my views about what IF actually is and what WD isn't :)

Indeed, as i talk about in this post on the role of nutrition in performance, under "intermittent fasting", colleagues have said IF is working for them (real IF where there are 16-24 hour plus fasts). So. Thar.

If someone like yourself has had success with your variant of the WD that's fab and good for you.

Thanks as always for stopping by.


Damen said...

I liked the way you deliberately mis-spelt "sole" as "soul" when you said "While some positive effects of fasting have been found, none of them are the soul domain of fasting" - presumably as an indirect indictment upon the claims that fasting has benefits upon one's spirituality (and hence, "soul"). Very clever.

adamchainz said...

Awesome post, this is very well written, and just what I was looking for when I was googling to research the science behind WD. I know it's old but thanks.


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