It’s one of the most popular books on weight loss. But here’s why “Wheat Belly” is a stomach full of weight-loss deception.
Editor’s note: This is part II of a combined post about common misconceptions on fat loss and weight gain. To read the first part, click here.
To help you understand why wheat isn’t the root of all evils, I’ve included an in-depth review of the claims made in Wheat Belly, as analyzed by Dr. Julie Miller Jones, Professor Emerita of Foods and Nutrition at St. Catherine University.
You can find the complete review and all study references here.
Wheat and Weight Loss
Davis’ Point: Elimination of wheat from the diet is the “holy grail” of weight loss. In his patient population, he recounts numerous occurrences of rapid, effortless weight loss of 10, 20, or even 50 or more pounds simply by elimination of wheat from the diet. He attributes the success of low-carbohydrate diets to the elimination of wheat.
What the Research Says:
Rapid weight loss often occurs with adhere to any weight loss diet in the short run. Studies and testimonials documenting dramatic weight loss abound, especially when the diets are low in carbohydrates (3-7).
Recommendations to eliminate wheat in conjunction with the other advice in this book reveal the Wheat Belly diet to be a low-carbohydrate diet. While it is truth that such diets have been shown to cause more rapid weight loss than other diets in the initial 6 months following such a regimen, they do not result in greater weight loss over time and result in more dropouts that other diet types that are more balanced and do not eliminate entire food groups.
Wheat and Obesity
Davis’ Point – Wheat consumption leads to central obesity. Central obesity stresses the heart, raises blood lipids, distorts insulin response, causes abnormal metabolic signals that affect every or- gan in the body, including the elevation of estrogen (which results in what he terms “men’s breasts”), and leads to inflammation.
What the Research Says:
Central obesity in the nutritional and medical literature is termed visceral adipose tissue (VAT). The facts Davis presents about central obesity are true and warrant concern.
What is not true is that wheat causes this condition and that elimination of wheat will cure this condition.
It is well documented that no one food or food group is responsible for VAT. Too many calories of any kind and too little exercise will result in VAT.
Recent data from the Framingham Heart Study cohort refute claims that wheat increases VAT. In fact, those who most closely adhered to dietary guidelines had the lowest VAT (17). Specifically, those who had the least visceral fat accumulation ate two servings per day of refined grains and three servings per day of whole grains (18).
Wheat and Expanding Waist Lines
Davis’ Point – The proliferation of wheat products parallels the increase in waist size.
What the Research Says:
Although the association may be true, this is an example of the misuse of correlations to imply causation.
First, the precise meaning of “proliferation of wheat products” is un clear. In many cases, less bread is eaten than was eaten in farm homes between 1900 and 1950.
However, more recent statistics from the U.S. Department of Agriculture Economic Research Service (USDA-ERS) show a 32% increase in wheat products since 1970 (19).
Davis does not report the more important information from the USDA-ERS paper (19), however, which notes, “A big jump in average calorie intake between 1985 and 2000 without a corresponding increase in the level of physical activity (calorie expenditure) is the prime factor behind America’s soaring rates of obesity and Type 2 diabetes…. Consumption in 2000 was 12 percent, or roughly 300 calories, above the 1985 level.”
Furthermore, many correlations can be made. Increasing waist size is associated with increased use of chewing gum, increased sales of running shoes, and the proliferation of high-fat ice creams, as well as any number of other products. Such associations are simply associations and do not prove causality.
The Twisted Glycemic Index
Davis’ Point – Whole-wheat bread has a glycemic index (GI) of 72, which is higher than table sugar (GI = 59).
What the Research Says:
Whole-wheat bread does have a GI higher than table sugar. GI is a measure that compares the blood glucose response elicited by 50 g of available carbohydrate from a food to the blood glucose response elicited by 50 g of glucose.
The GI of table sugar (sucrose) is directly related to its composition, which is half high-GI glucose and half low-GI fructose. Thus, the mixture of these two sugars results in a moderate GI, one that is lower than whole-wheat bread.
One aspect of GI that is frequently misunderstood is that the measure is often used to compare very different amounts of food. Fifty grams of sucrose or glucose (approximately 3 tablespoons) would yield fifty grams of available carbohydrate.
Fifty grams of available carbohydrate from whole wheat bread is much more than fifty grams of bread since bread is not all carbohydrate, and all the carbohydrate is not available.
Thus, it would take 144 g of whole-wheat bread (5.1 slices at 28 g per slice) or 111 g of white bread (3.9 slices) to yield 50 g of available carbohydrate.
Starches, Insulin, and Weight Loss
Davis’ Point – The relationships between blood glucose, insulin response, and GI, as described by Davis, include the following:
1) Whole-wheat bread consumption results in the same blood glucose response as white bread consumption: “Eating 2 slices of whole wheat bread increases blood sugar more than a candy bar.”
2) Pasta has a lower GI because of the compression of the wheat flour, but it does raise blood sugar at 4–6 hr.
3) A three-egg omelet causes no rise in blood sugar and no increase in insulin.
4) Whole-wheat bread consumption results in higher blood sugar levels than kidney beans or potato chips.
What the Research Says:
Davis’ statements regarding the relationships between blood glucose, insulin response, and GI are inaccurate and misleading.
1) Whole-wheat bread consumption does produce the same glucose response as white bread consumption. This statement by Davis is accurate; however, most users of the GI and glycemic load (GL) are unaware that the amount of bread is different.
It takes more whole-wheat bread than white bread to obtain the same glucose response.
Although it is also correct that wholewheat breads have a higher GI than a candy bar such as a Mars or Snickers bar, as previously mentioned the GI compares 50 g of available carbohydrate, which is about 4 slices of whole-wheat bread and about 2.5 oz of Mars bar, so the volume of food is different.
In addition, there are several factors involved in available carbohydrate levels, including the fat content of the food, which impedes amylase activity; other components such as nuts, a naturally low-GI food; and the rich phenolics and antioxidants in the chocolate, which lower the GI of the candy bar.
In short, because the calories and nutrients delivered by the two products are so vastly different, it is not possible to make a direct comparison that is meaningful.
It should also be pointed out that not all whole-wheat breads yield higher GIs; for example, some sourdough whole wheat breads (23) have a GI < 56, which is the value quoted for a Mars bar.
2) Pasta does have a lower GI than bread because the dense structure of the pasta impedes amylases from readily accessing the carbohydrate and, therefore, does not increase blood sugar rapidly (24).
Davis implies there is a problem because the pasta delivers glucose over a longer period of time. However, slow, steady delivery of glucose into the bloodstream is considered advantageous because it avoids large swings in blood sugar. Further, there is a ready supply of glucose for the brain and for use by cells throughout the body.
3) To state that an omelet causes no rise in blood sugar reveals a misunderstanding of the relationship between foods and their effects on blood sugar.
Although it is true that foods that do not contain carbohydrate do not raise blood glucose to a significant degree, the ingestion of protein can impact blood glucose by causing insulin release and through its digestion produce amino acids that are glucogenic.
Further, stating that an omelet does not raise insulin is incorrect. All food proteins stimulate insulin release (25), although not all stimulate its release to the same degree.
Foods such as milk, which has a very low GI, have a great capacity to stimulate insulin release through the release of incretin hormones and the presence of insulinotropic amino acids.
4) Whole-wheat bread does yield higher blood sugar than kidney beans or potato chips for several reasons. First, beans are a great source of dietary fiber, some of it soluble, which lowers blood glucose response.
Second, the carbohydrate in beans is less available. Potato chips have a lower glycemic response than whole-wheat bread because they contain more than 35% fat, and fat impedes amylases.
Further, starch in potato chips has been cooked and cooled, causing the starch molecule in the food to crystallize and produce a lower glycemic response.
Wheat Belly uses charges about the evils of wheat to tout the value of low-carbohydrate diets. While these diets have been shown to promote rapid weight loss in the medium term (6 months) and may be advantageous for individuals with metabolic syndrome and abnormal glucose tolerance, they have not been shown to be long-term solutions to obesity for most people.
The above statements were originally sourced from: “Wheat Belly—Analysis of Selected Statements and Basic Theses from the Book,” authored by Julie M. Jones, Cereal Foods World 57(4):177-189, 2012, AACC International, St. Paul, MN.