A new framework for understanding obesity

Excess weight is commonly understood to be caused by an energy imbalance—more calories consumed than expended over the course of the day. A new study co-authored by researchers from Harvard T.H. Chan School of Public Health argues that this framework is incorrect. In its place, the authors propose a carbohydrate-insulin model (CIM) for understanding obesity. According to the CIM, obesity is the result of a dysregulated hormonal and metabolic response to the carbohydrates people eat.

The study was published September 13, 2021, in The American Journal of Clinical Nutrition.

Co-author Gary Taubes, a science and health journalist, described the CIM model in a September 13 opinion piece in STAT: “People don’t get fat because they eat too much, consuming more calories than they expend, but because the carbohydrates in their diets—both the quantity of carbohydrates and their quality—establish a hormonal milieu that fosters the accumulation of excess fat.”

The authors recommend substituting carbohydrates with a high glycemic load (a measure of their impact on blood sugar) like refined grains, potato products, and sugary foods with high-fat foods such as nuts, seeds, avocados, and olive oil, which have no impact on blood sugar.

Harvard Chan School authors of the study included David Ludwig and Walter Willett.

Read STAT opinion piece: How a ‘fatally, tragically flawed’ paradigm has derailed the science of obesity