Low-carbohydrate ketogenic diets promote weight loss. Several well-controlled studies found that people on low-carb diets lost more weight than people following mixed diets, even though they consumed the same number of calories.

A study on rats by researchers from the Beth Israel Deaconess Medical Center in Boston, Massachusetts may have provided an explanation. Low-carbohydrate diets cause ketone formation, which are chemicals released due to the incomplete breakdown of fats. Ketones activate genes that promote fat breakdown, increase energy expenditure and impair fat storage.

Low-carbohydrate diets don’t violate the law of conservation of energy (energy is neither created nor destroyed). They increase blood ketones, which activate genes that increase energy expenditure and dissipate more calories than normal, which promotes weight loss. The researchers concluded that ketogenic diets induce a metabolic state that promotes weight loss. [source: American Journal of Physiology Endocrinology and Metabolism]