Very low-carbohydrate diets have experienced a resurgence in popularity, perhaps due to their great weight-reducing potential. Recent clinical trials have shown greater weight loss with a very low-carbohydrate diet compared to a low-fat diet. This suggests a metabolic advantage and evidence opposed to the notion that "a calorie is a calorie."
Metabolic advantage is proclaimed to be a violation of the first law of thermodynamics and mistakenly used to support the notion "a calorie is a calorie." However, very low-carbohydrate diets enhance mobilization and utilization of fat while sparing carbohydrate fuel sources. These diets also utilize different chemical pathways and appear to decrease efficiency, which means that more of the food you eat is lost as heat, therefore not violating the first law of thermodynamics. Very low-carbohydrate diets also suppress appetite and energy intake, which is partially due to the inhibitory effects of ketones.
In summary, recent findings of several randomized clinical trials comparing very low-carbohydrate and low-fat diets requires that this "non-conventional" diet approach must seriously be considered as a viable treatment for weight loss.