Our Daily Bread

“There is no reason to be eating fewer carbs—they’re not the enemy,” says UVA exercise physiology professor Glenn Gaesser. He published an extensive analysis of peer-reviewed, scientific research on carbohydrate consumption, glycemic index and body weight in the October issue of the Journal of the American Dietetic Association. Prevailing wisdom holds that so-called “bad” carbohydrates will make you fat, but Gaesser says, “that’s just nonsense.” His findings indicate that diets high in carbohydrates are almost universally associated with slimmer bodies. More importantly, Gaesser found that consuming lots of high-glycemic foods is not associated with higher body weights. In fact, several large U.S. studies revealed that high-glycemic diets were linked to better weight control. 

The labeling of carbohydrates as “good” or “bad” is based on a glycemic index (GI), which measures the quality of a carbohydrate in terms of how much it raises one’s blood sugar level. Foods with a high GI are generally thought to be bad because they raise blood sugar more than other types of carbs—a condition that proponents of the glycemic index claim leads to excessive insulin secretion, which can cause weight gain and health problems. Foods such as whole-grain breads are said to offer “good” carbs because they have a lower GI than white bread.

After looking at hundreds of articles on large-scale studies using surveys or randomized, controlled trials, Gaesser says they show that “people who consume high-carb diets tend to be slimmer, and often healthier, than people who consume low-carb diets.” Even high-glycemic foods have a place in the diet, he says, attributing that to the overall higher quality of a high-carbohydrate diet, which includes more fiber-rich and other nutritional foods.

He also found no compelling evidence that avoiding carbohydrates with a high GI helps prevent type 2 diabetes, heart disease or cancer.

Reducing any part of the diet—carbs or proteins or fats—will result in modest weight loss in the short term if calorie consumption is reduced, Gaesser says, but a high-carb, low-fat diet is still the best strategy for long-term weight maintenance.