Advocates of ketogenic diets for weight loss claim that ketogenesis can lead to a “metabolic advantage” that helps burn 10 times more fat and an extra 400 to 600 calories per day — the same as a vigorous session of physical activity. The main scientific model that’s used to explain that advantage is the ”carbohydrate-insulin hypothesis,” which has been promoted by experts like Harvard professor David Ludwig, Obesity Code author Jason Fung, journalist Gary Taubes, and pediatric endocrinologist Robert Lustig, among others.
Once ketogenesis kicks in and ketone levels are elevated, the body is in a state called “ketosis,” during which it’s burning stored fat. There are a few ways to get into ketosis. One is through fasting: When you stop eating altogether for an extended period of time, the body will ramp up fat burning for fuel and decrease its use of glucose (which is part of the reason people can survive for as long as 73 days without food).