Many people who lose weight intentionally struggle to maintain their lower weight. In the carbohydrate-insulin model of obesity, a high glycaemic load increases the blood insulin-to-glucagon ratio, which results in increased hunger, lower energy expenditure, and weight gain. To test this model, researchers examined the effects on total-energy (Kcal/day) expenditure of three diets with different carbohydrate-to-fat ratios.

Researchers randomised 164 adults (body-mass index, ≥25 kg/m2) to high-, moderate-, or low-carbohydrate diets (60%, 40%, and 20% carbohydrates, respectively) with inverse proportions of fat (20%, 40%, and 60% fats, respectively). Diets had a fixed amount of protein (20%), and total energy intakes to maintain weight loss.

After 20 weeks, the intent-to-treat analysis showed higher total energy expenditure in the moderate- and low-carbohydrate groups (mean, 91 Kcal/day and 209 Kcal/day, respectively).

The effect of the low-carb diet on improving total energy expenditure was even greater in the subgroup of people whose pre-weight loss insulin levels were in the highest tertile.