ROCKVILLE, Md. — Overeating obviously leads to excess weight, right? A team of scientists says not so fast, it’s actually what you eat, not how much you eat that leads to obesity. Their study finds processed food and rapidly digestible carbohydrates may be what’s really behind society’s growing waistline.
According to the Centers for Disease Control and Prevention (CDC), over 40 percent of American adults classify as obese. This places nearly half the population at higher risk of heart disease, stroke, and type 2 diabetes. The USDA’s current Dietary Guidelines for Americans for 2020 to 2025 maintains the belief that losing weight “requires adults to reduce the number of calories they get from foods and beverages and increase the amount expended through physical activity.”
However, study authors say this age-old energy balance model for weight loss doesn’t actually work in a world full of highly palatable, heavily marketed, cheap processed foods. The team adds that despite years of public health messaging about eating less and exercising more, cases of obesity and obesity-related diseases continue to rise.
They claim their new carbohydrate-insulin model better explains the global trend towards obesity and weight gain, noting that the model even points to more effective and long-lasting weight loss strategies.
“During a growth spurt, for instance, adolescents may increase food intake by 1,000 calories a day. But does their overeating cause the growth spurt or does the growth spurt cause the adolescent to get hungry and overeat?” says lead author Dr. David Ludwig, an endocrinologist at Boston Children’s Hospital and Professor at Harvard Medical School, in a media release.
Dr. Ludwig adds the old energy balance model doesn’t explain the biological causes of weight gain.
Your menu choices are more to blame
Unlike the energy balance model, study authors say the carbohydrate-insulin model claims overeating is not the main cause of weight gain. Instead, the researchers say consuming foods with a high-glycemic load are the real culprit. These foods include processed, rapidly digestible carbohydrates.
The study finds such foods also cause hormonal responses which alter an eater’s metabolism, drives fat storage, and leads to weight gain. When people consume carbohydrates, the body increases the amount of insulin it secretes. This signals fat cells to store more calories and leaves fewer calories for the body to use as muscle fuel.
As a result, the brain thinks the body isn’t getting enough energy to keep going and starts sending out the hunger signals. Moreover, researchers say a person’s metabolism can also slow down as the body tries to “conserve fuel” — thinking it’s still hungry. It’s a vicious cycle that leaves people thinking they’re still hungry and continuing to pile on more non-filling food.
“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. As a result, people may lose weight with less hunger and struggle,” Dr. Ludwig says.
The findings appear in The American Journal of Clinical Nutrition.