High protein, low carbohydrate diets may promote weight loss by shifting fuel use from carbohydrates to fat when carbs are not available in the diet. An Australian study showed that the body could convert amino acids (protein) into carbohydrates in the lever by a process called gluconeogenesis. Researchers compared blood sugar and fat levels in people who followed a three day starvation diet; a three day high protein, low carb diet; or a three day mixed diet.

Blood sugar decreased and blood fats increased during the starvation diet, but did not change during the high protein/low carb or mixed diet. The amino acids from proteins can be converted to carbohydrates in the liver when carbs are unavailable in the diet. High protein diets probably promote weight loss by preventing hunger and restricting food intake. (Metabolism, 59: 1633-1641, 2010)