Have you ever wondered how low carb but higher fat diets actually work? Surprisingly, one answer may lie in your liver. Researchers at Beth Israel Deaconess Medical Center (BIDMC) have identified a liver hormone known as FGF21 which is required to oxidize fatty acids - and thereby burn calories. According to the senior author of the study, "When the diet is extremely low in starches and sugars, blood sugar levels drop substantially so that the muscles and brain have to turn to alternative fuels... consequently, fatty acids are broken down in the liver and converted to ketones, which then serve as a major fuel source."
The metabolic state known as ketosis, is characterized by low insulin levels which would be experienced during fasting, starvation, or while consuming a low-carb diet. Research on the metabolic states of animals suggest that it's not just how many calories you consume, but the type of calories that make the difference.
So, based on this research, what sort of diet would be recommend? "Diets that limit carbohydrates and eliminate transfats, and at the same time emphasize fiber and good fats, appear to be healthiest, especially among individuals who are predisposed to developing diabetes."