My girlfriend gave me a copy of Wheat Belly by William Davis. Being a science guy I wanted to read it critically and gather some other evidence of my own. I tend not to trust faddish diet books. Co-incidentally, the same question came up on the Ultra mailing list and I was lucky enough to get a large number of references. This review is only selected because it’s based on the links I received (which might be selected by senders who wish merely to convince me). Sadly, I do not have access to a scientific literature database nor the background to use it well.
Masterjohn: Cholesterol and Health Blog
I posted a question on the Fitness StackExchange site which yielded a link to a blog post by Chris Masterjohn who is “pursuing a PhD in Nutritional Sciences with a concentration in Biochemical and Molecular Nutrition at the University of Connecticut.”
According to his bio, Mr Masterjohn is a former vegetarian whose failing health lead him to start eating organ meats, butter, eggs, etc. in order to regain his health. Hence, he would appear to be not on the side of the nutritional mainstream when it comes to a low fat diet.
His blog post is a chapter by chapter review of the science, including references, and is critical of some of the science (most especially around whether advanced glycation endproducts (AGE) are merely useless debris, as Dr Davis suggests, or perhaps a signalling mechanism.
Quoting from his conclusion,
Despite disagreeing with some of the points in Wheat Belly, I think Dr. Davis is essentially correct that modern wheat products are representatives of the type of hubris that is destroying the health of modern humans…
While there is no doubt that there are people who should avoid wheat altogether, I am left with doubts about whether all wheat past the point of einkorn and emmer must be banished from the human diet in order to lead the majority of us back to health. McCarrison’s belief that it is primarily “the enforced restriction to the unsophisticated foodstuffs of nature” combined with a healthy dose of wisdom that is required for “long life, continued vigor, and perfect physique” remains compelling to me.
But I do agree that the processed junk Dr. Davis calls “wheat” should be purged from the diet, that the development of dwarf wheat has taken its toll on us, and that we should steer clear of the packaged foods and meet Dr. Davis for a pow wow in the produce aisle.
Noakes: Sorry but carbo is really a no-no
Dr Noakes is a professor of exercise science and sports medicine at the University of Cape Town is well known for his book The Lore of Running which is considered the bible of all things running. He is also a recognised world expert in exercise-associated hyponatremia. He was recently quoted in a newspaper article in the Sunday Times of South Africasaying that he had been tested as being carbohydrate resistant and had lost 15kg on a low carbohydrate diet.
Phinney: Ketogenic diets and physical performance
Henry Baker calls this the classic paper on athletic performance in a non-carb diet. Ketogenic refers to a diet which produces ketosis – which is how fat is burned. The abstract reads,
Impaired physical performance is a common but not obligate result of a low carbohydrate diet. Lessons from traditional Inuit culture indicate that time for adaptation, optimized sodium and potassium nutriture, and constraint of protein to 15–25 % of daily energy expenditure allow unimpaired endurance performance despite nutritional ketosis.
This paper is interesting for how it starts with the diets of some traditional hunter-gatherer diets and how this knowledge came to be known by Western science through such things as an expedition to find the lost Royal Navy Franklin expedition. The author proceeds to show how he tested the diet including controlling the diet of competitive bicycle racers to be very low in carbs (2% of energy), very high in fat (83%) with 15% of energy and protein supplemented with additional sodium, potassium, magnesium, calcium and a multi-vitamin.
The result was the the bicycle racers’ performance got worse for a week and then their aerobic performance was fully restored.
Gary Taubes is an American science writer who has written two books on diet (as well as other science books). There were a number of reviews of his work and an article from the author himself.
Tierney: Diet and Fat: A Severe Case of Mistaken Consensus
This is a review in the New York Times of Gary Taubes’ book, Good Calories: Bad Calories. It provides a history of the political machinations by which the current carb-heavy food pyramid came to be. However, it provides no real critique of the underlying theory itself. . Mr Tierney says:
As Mr. Taubes notes, the most rigorous meta-analysis of the clinical trials of low-fat diets, published in 2001 by the Cochrane Collaboration, concluded that they had no significant effect on mortality.
The Cochrane Collaboration is a not for profit organisation which aims to organize research information in a systematic way. They are known for systematic reviews of randomized trials. This means they are a good source for summaries of the evidence on a given medical question.
When I searched their website I couldn’t find anything which seemed to match the quote above. However, I did find asummary from 2011 which said (emphasis mine),
Modifying fat in our food (replacing some saturated (animal) fats with plant oils and unsaturated spreads) may reduce risk of heart and vascular disease, but it is not clear whether monounsaturated or polyunsaturated fats are more beneficial. There are no clear health benefits of replacing saturated fats with starchy foods (reducing the total amount of fat we eat). Heart and vascular disease includes heart attacks, angina, strokes, sudden cardiovascular death and the need for heart surgery. Modifying the fat we eat seems to protect us better if we adhere in doing so for at least two years. It is not clear whether people who are currently healthy benefit as much as those at increased risk of cardiovascular disease (people with hypertension, raised serum lipids or diabetes for example) and people who already have heart disease, but the suggestion is that they would all benefit to some extent.
Bubnoff: Still against the grain and high on fat
This is a Q & A session with Taubes to promote is book in the LA Times in 2007. Taubes is quoted,
It’s never been demonstrated that people who eat these “healthy” low-fat diets live longer, which is, after all, what we all hope to do. The latest example was the Women’s Health Initiative trial — published two years ago — of 49,000 women. It cost upward of half a billion dollars, and it simply failed to confirm the idea that if you eat less fat or more fruits and vegetables or more fiber or less meat you will live longer.
That statement is (largely) true. From the press release from the US National Heart, Lung and Blood Institute,
Following an eating pattern lower in total fat did not significantly reduce the incidence of breast cancer, heart disease, or stroke, and did not reduce the risk of colorectal cancer in healthy postmenopausal women, according to the latest clinical trial results from the National Institutes of Health’s Women’s Health Initiative (WHI).
Taubes: Is Sugar Toxic?
This is an article by Taubes himself in the New York Times discussing a 2009 lecture by Robert Lustig. Taubes then goes on to examine some of the science linking sugar consumption to a fatty liver which leads to metabolic syndrome and diabetes. His conclusion is,
Sugar scares me too, obviously. I’d like to eat it in moderation. I’d certainly like my two sons to be able to eat it in moderation, to not overconsume it, but I don’t actually know what that means, and I’ve been reporting on this subject and studying it for more than a decade. If sugar just makes us fatter, that’s one thing. We start gaining weight, we eat less of it. But we are also talking about things we can’t see — fatty liver, insulin resistance and all that follows. Officially I’m not supposed to worry because the evidence isn’t conclusive, but I do.
Gadsby: The Inuit Paradox: How can people who gorge on fat and rarely see a vegetable be healthier than we are?
This article, from Discover Magazine, discusses the traditional Inuit diet and the effect of a traditional Western diet on the health of Inuit communities.
There have been a number of studies of how migrating birds fuel themselves to travel incredibly long distances with very little, if anything to eat. The answer given is large amounts of fat. I would argue that these studies are interesting but not convincing because birds and humans diverged around 160 million years ago. We are too dissimilar for much about diet to be convincing.
Brown: Wind tunnel helps show how birds fly so far without water
This 2011 article from the LA Times discusses a small study of fuel usage by birds during migration.
But the results gathered from the compliant birds demonstrated uniformly that the thrushes were burning muscle and organs to get water, Gerson said. No birds became dehydrated, and all burned significantly more protein tissue under dry conditions than under wet conditions. Blood tests confirmed the measurements.
Zimmer: 7,000 Miles Nonstop, and No Pretzels
This is a 2010 article from the New York Times discussing long distance migration by birds:
As Mr. Gill observed when he first observed bar-tailed godwits, a long journey requires a lot of food. It turns out that long-distance migrators will enlarge their liver and intestines as they feed, so that they can convert their food as fast as possible. They build up large breast muscles and convert the rest of their food to fat.
By the time the birds are ready to leave, their bodies are 55 percent fat. In humans, anything more than 30 percent is considered obese. But as soon as the birds are done eating, their livers and intestines become dead weight. They then essentially “eat” their organs, which shrink 25 percent. The birds use the proteins to build up their muscles even more.
Jenni-Eiermann: Fuel use and metabolic response to endurance exercise: a wind tunnel study of a long-distance migrant shorebird
This is a study published in the Journal of Experimental Biology. The abstract reads,
This study examines fuel use and metabolism in a group of long-distance migrating birds, red knots Calidris canutus (Scolopacidae), flying under controlled conditions in a wind tunnel for up to 10 h. Data are compared with values for resting birds fasting for the same time. Plasma levels of free fatty acids, glycerol and uric acid were elevated during flight, irrespective of flight duration (110 h). Triglyceride levels, the estimated concentration of very-low-density lipoproteins (VLDLs) and b-hydroxybutyrate levels were lower during flight, while glucose levels did not change. In flying birds, plasma levels of uric acid and lipid catabolites were positively correlated with the residual variation in body mass loss, and lipid catabolites with energy expenditure (as measured using the doubly labelled water method), after removing the effect of initial body mass. The plasma metabolite levels indicate: (i) that the rates of
catabolism of lipids from adipose tissue and of protein are higher during flight; (ii) that low ketone body
concentrations probably facilitate fatty acid release from adipose tissue; (iii) that low triglyceride and VLDL levels do not indicate the use of an additional pathway of fatty acid delivery, as found in small birds; and (iv) that the relationships between energy expenditure, body mass loss and metabolic pattern suggest that a higher individual energy expenditure entails a higher rate of catabolism of both lipids and protein and not a shift in fuel substrate.
Schulman: Fuel On Fat For The Long Run
This is an article published in 2002 in Marathon and Beyond discussing optimal diet for long-distance running. From the article,
At issue, however, was the intensity of exercise used for the tests. High-fat diets improved endurance at relatively low-intensity levels. When the intensity was increased to mirror race situations, the advantage disappeared. The higher- intensity exercise required more carbohydrate, and the subjects simply lacked adequate glycogen to continue for extended periods. The lesson is that you can reduce your reliance on carbohydrate, but you can’t eliminate it.
We now know that both high-carbohydrate and high-fat diets cause fatigue and poor performances. The best diet is probably somewhere in between: one that supplies enough fat to stimulate fat metabolism and maintain production of testosterone and estrogen and also supplies enough carbohydrate to keep the brain and nervous system happy and the glycogen stores filled. Many sports scientists are recommending a basic diet that supplies 50 percent carbohydrate, 30 percent fat, and 20 percent protein, with additional carbohydrates after hard or long-duration training.
The science in Wheat Belly is at least credible. While some of Dr Davis’ claims are contestable there is good evidence that a low-carb diet can support athletic performance and has benefits in losing weight. However, there appears to be not enough science to be firm in that conclusion.