A popular theory asserts that carbohydrates in food cause a spike in insulin, which promotes fat storage and increases appetite, leading to overeating.
However, recent research suggests that this “carbohydrate-insulin model” may be an oversimplification.
In an article in the journal Science, researchers argue that while low carb, high fat diets can help some people lose weight, a more nuanced model is needed to explain how they work.
They write that insulin levels between meals, and the hormone’s effect on multiple organs, are more important for balancing the body’s energy budget.
For decades, the causes of obesity — and the most effective way to lose weight — have been the subject of fierce debate among scientists and healthcare professionals.
According to one theory, known as the “carbohydrate-insulin modelTrusted Source,” food and drink that contain large amounts of carbohydrates cause a spike in circulating insulin levels.
The hormone drives fat cells, or “adipocytes,” to store the excess calories, which reduces the availability of these energy sources for the rest of the body.
This, in turn, increases hunger and slows metabolism, which leads to weight gain over time.
Dietitians often cite the carbohydrate-insulin model to explain the success of high fat, low carbohydrate diets such as the ketogenic diet.
Unlike carbohydrates, dietary fat does not cause a spike in insulin levels immediately after a meal.
On the other side of the debate, the energy balance modelTrusted Source makes less of a distinction between fat and carbohydrates.
This model focuses instead on the balance between total calorie intake through eating and drinking, and total calorie expenditure through physical activity.
According to this model, if calorie intake exceeds expenditure, the result will be weight gain over time. But if expenditure exceeds intake, the eventual outcome will be weight loss.
Writing in the journal Science, two scientists argue that the carbohydrate-insulin model is overly simplistic.