Eating foods high in easily digested carbohydrates, rather than overeating, is likely to be a major cause of the obesity epidemic, according to a new article published in the American Journal of Clinical Nutrition.
The article examines a central claim that has been made countless times in recent decades — that the cause of obesity is taking in more energy than a person burns. Without disputing that people are taking in more calories than they burn when they gain weight, the article’s authors dispute that this counts as an explanation for why people gain weight. As a counterexample, “During a growth spurt, for instance, adolescents may increase food intake by 1,000 calories a day,” said article author David Ludwig, MD, in a press release on the article. “But does their overeating cause the growth spurt or does the growth spurt cause the adolescent to get hungry and overeat?”
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Ludwig, an endocrinologist at Boston Children’s Hospital, and coauthors argue that in much the same way, the energy imbalance or overeating that drives obesity is caused by hormonal activity that activates fat storage in the body. And the main reason for this process, they claim, is something called the carbohydrate-insulin model. This model holds that a high intake of easily digested carbohydrates — largely in the form of highly processed sugars and starches — leads to hormonal responses, including the insulin response, that changes a person’s metabolism and leads to out-of-control fat storage.
The essence of the insulin-carbohydrate model is that when someone eats easily digested carbohydrates, the body responds by secreting more insulin and secreting less glucagon. As a result, the body’s fat cells are activated to store more energy (calories), leaving less energy available for muscles and other key active uses of energy in the body. With less energy available for important functions, the brain increases hunger signals. And when this hunger leads to a person eating even more easily digested carbohydrates, the process goes on in a cycle.
The article authors note that the insulin-carbohydrate model isn’t new, and in fact has been around for over a century. But they claim that the evidence they include in the article represents the strongest and most comprehensive case for the model that has yet been published. What’s more, they write, they have identified hypotheses that can be tested in future studies to evaluate the model. For example, if the model is valid, then a diet that’s low in highly processed carbohydrate-rich foods should lead to greater sustained weight loss than simply trying to reduce calorie intake while eating these highly processed foods.
“Reducing consumption of the rapidly digestible carbohydrates that flooded the food supply during the low-fat diet era lessens the underlying drive to store body fat,” said Ludwig. “As a result, people may lose weight with less hunger and struggle.”
Want to learn more about weight management? Read “Tried and True Weight-Loss Techniques,” “Losing Weight Without Feeling Hungry: Eight Tips,” and “Seven Ways to Lose Weight.”
