Gary Taubes is a science writer who embarked on a project to collect what real science can tell us about the growing problem of obesity. In his book, Why We Get Fat and What to Do About It, he says that part of the problem is that we have embraced a very simple dogma for decades. The dogma is that obesity is a matter of too much stored energy (calories); if you simply control the calories you take in or you increase your energy expenditure by exercise, you will lose the stored fat. The fundamental argument against that simplistic thinking is that it isn’t working.
The Obesity Epidemic
We are faced with a growing epidemic of obesity worldwide. Taubes’ review of the literature shows ample documentation that when you increase your energy expenditures with increased exercise, you will also typically increase your appetite and food intake. He cites numerous animal and human studies demonstrating that increased exercise actually increased body fat.
Jean Mayer, PhD, a renowned scientist, physiologist and nutritionist, was a huge proponent of the theory that a sedentary lifestyle was the cause of obesity. Taubes explains that Mayer’s thinking was based on the fact that “his job never required that he reduce a fat person to a healthy weight, so his ideas were less fettered by real-life experience,” yet Mayer had a strong influence on the popular press.
Hormonal Influences on Weight
Taubes also cites an interesting experiment done in the early 1970s that involved removing the ovaries from female rats. After the surgery, the rats ate voraciously and became obese. According to the calories in/calories out theory, the rats would become obese because they ate more. However, when another group of female rats had their ovaries removed and also had their food intake restricted, they became fat just as quickly and also became very sedentary. Now, you could argue that the low energy expenditure led to obesity. However, when estrogen was given back to the rats, they were able to return to normal size, along with normal food intake and normal activity. Taubes explains that what we learned from this experiment is that the removal of the ovaries causes a disruption of the fat tissue, leading to a drive to get fatter either by overeating or restricting energy output. Estrogen, as it turns out, inhibits the activity of an enzyme called lipoprotein lipase, which tends to pull fat into fat cells or muscle cells.
As Taubes suggests, the physiology of fat cells is complex and involves many hormones and enzymes. Insulin is the hormone that trumps them all: the higher the level of insulin, the greater the tendency to store fat. The trigger for increasing insulin is the type of food we eat. Carbohydrates such as fructose, sugar, soda, cereal, bread, potato, alcohol, and pasta all trigger greater insulin levels. High-fructose corn syrup, which was introduced in the late 1970s, includes about 42% glucose. This combination is now thought to be one of the most fat-creating substances around.
The answer to the obesity problem, according to Taubes, is to return to a more Paleolithic diet, with an emphasis on protein (particularly animal protein) and fats. Carbohydrates should be restricted to low-glycemic vegetables such as green leafy vegetables. Depending upon the carbohydrate sensitivity of the individual, the amount of carbohydrates may need to be very restricted in some cases. The food pyramid, which puts meat and fats at the top to be used sparingly while breads and pastas are at the bottom to be used liberally, should be inverted.
Why We Get Fat is a welcome read, but it is not a book full of recipes and menu guides. It contains and/or references useful scientific information from reputable sources. For example, according to the Lifestyle Medicine Clinic at Duke University, those interested in weight loss should limit their daily intake of carbohydrates to 20 grams per day. This, along with other guidelines, can be found in the Appendix.
Gary Taubes summarizes why this book should be of interest to those grappling with obesity: we “westernized” our diets with too many carbohydrates, and while doing so we also “westernized” our health with the introduction of cancers, heart disease, diabetes, arthritis, and more. It is time to step back and sort through the food and diet industry propaganda to find out what really works.