The third chapter of Wheat Belly spends more time on the negative health effects of wheat, but again, the focus is almost entirely on celiac disease. The crux of the book’s argument against wheat is its high glycemic index. Glycemic index is a calculated figure used to determine how much a person’s blood sugar will be affected by eating a given food. But wheat doesn’t cause diabetes or chronically high blood sugars even though its glycemic index is high as we will see.
As Dr. John McDougall famously points out, the reason that you eat food is to raise your blood sugar; so this is hardly a reason to abandon foods that have nourished human beings for at least ten millennia. The most bothersome thing about the book though is that the scientific justification for avoiding wheat and other starchy carbohydrates is absent (the book has a heading WHEAT: SUPERCARBOHYDRATE). Beyond that, the explanation that wheat causes diabetes has been disproven by countless peer-reviewed publications which the book ignores.
The facts about insulin and carbohydrates are clear and have been for decades. High fat diets cause insulin resistance, obesity and diabetes. Giving healthy people high fat diets can create diabetic level glucose tolerance tests within a period of days. Additionally, low-fat diets composed largely of complex, starchy carbohydrates reverse insulin resistance and can cure diabetes. The most important number to determine the insulin response for a food is not the glycemic index, but the insulin index. This is the total amount of insulin the body releases when we eat a given food. So we want to know which foods have the highest insulin index if we want to avoid insulin resistance, obesity and diabetes. Yet the book gets this mostly wrong when it says:
The higher the blood glucose after consumption of food, the greater the insulin level, the more fat is deposited. This is why, say, eating a three-egg omelet that triggers no increase in glucose does not add to body fat, while two slices of whole wheat bread increases blood glucose to high levels, triggering insulin and the growth of fat, particularly abdominal or deep visceral fat.
This paragraph from the book is not true. If the cause of the growth of fat is insulin, then the biggest problem foods should be the ones that create the most insulin response, not the ones that make the most blood sugar response. The paragraph above seems to argue you can eat omelets and the calories in those omelets cannot be converted into body fat somehow. This is magical thinking. Of course an omelet can be converted to body fat and in fact, most readers will know people who eat omelets regularly and yet are still fat. The facts is that a study published in 2010 in Nutrition by Dr. Shi showed that egg consumption actually increase the risk of diabetes 300% when someone eats only one egg per day. Similar studies have shown similar numbers for egg consumption. The book doesn’t explain how those findings can be if its recommendations are correct. It ignores them as if they don’t exist.
The insulin index of various foods is well-known. Bread is not a major contributor to total insulin response. White bread has an insulin index of about 140, wheat bread around 122. White rice is around 69, potatoes 120, french fries are 146. Beef is 1583, cheese is 268 and a single egg comes in at 135. So while the book is telling you to eat eggs instead of bread or to eat as much cheese as you want to keep your insulin level low, decrease abdominal fat and avoid diabetes the facts are really the reverse. As Ari Whitten and Dr. Wade Smith say in their new book, The Low Carb Myth:
If we look at a chart of the insulin index of foods, we find something remarkable. Many protein- and fat-containing foods – foods commonly advocated on low-carb diets with the specific rationale that those foods are good because they keep insulin low – actually increase insulin levels to a similar, and sometimes even greater, degree than many high-carbohydrate containing foods!
What the reader of Wheat Belly won’t find out is that the best scientific evidence goes completely against the foods that Wheat Belly is suggesting that you replace wheat with. The real story on wheat and obesity is that almost all studies conclude that eating whole grain regularly reduces obesity dramatically. Getting rid of saturated fat in a diet reduces obesity dramatically. The countries that eat the highest percentage of calories from carbohydrate per capita have the lowest rates of obesity. The book doesn’t even discuss these studies. The reader of the book will not know that they exist.
The most misleading section though is on weight loss in celiac patients who adopt a gluten free diet. The book tries to assert that gluten free diets create weight loss in celiac patients, while this is clearly not true. Most celiac patients are too skinny and sick due to their chronically inflamed intestines. In fact, one of the simple ways a doctor uses to determine if a patient truly has celiac disease is that the patient will gain weight when removing gluten from the diet. The weight is gained usually because the intestines become more able to absorb nutrients. The book refers to a study of celiac patients on a gluten-free diet, published by Dr. Murray from Mayo clinic in AJCN in 2004, in which the average patient gained weight, some as much as 90 lbs. The book claims that 215 patients were obese in this study, but at the beginning of the study, only 27 patients were obese (yes, the book is that wrong), at the end of the study, 19 were still obese. If wheat removal only caused weight loss in a minority of the obese patients who have celiac disease, why would we expect better results from the general population? Remember, the book all but guarantees that if somebody loses the wheat they will lose weight. Yet a majority of patients with obesity and celiac disease in this study did not lose any significant weight.
The book then talks about gluten. My previous posts in this series have shown that the 5% difference in gluten proteins is insignificant compared to the 43% changes in chicken protein. Then the book mentions that some people are allergic to wheat. However, there are some people who are allergic to many foods, but we don’t generalize that allergy into a recommendation for the whole population to avoid those foods. There are people who are allergic to eggs, dairy products and shellfish, but the book is happy to recommend these foods.