It is possible to lose weight without eating carbohydrates, and one of the more effective diets is the ketogenic diet, which is a very low-calorie carbohydrate diet. Most of the calories are mainly provided by fats and proteins, and the proportion of carbohydrates in this diet structure is very small. The theory behind weight loss is that under normal circumstances, carbohydrates enter the gastrointestinal tract and are quickly digested, absorbed, decomposed and converted into glucose, and the calories needed for daily activities are provided by the decomposition of this glucose, and not by the decomposition of fat. If there is no breakdown of fat, it will not play a role in weight loss. If the amount of carbohydrates consumed is very small, the glucose produced by the decomposition of carbohydrates is very small and cannot meet the body’s caloric needs, and it is necessary to decompose fat to produce calories to meet daily activities. While decomposing fat, it will lead to weight loss and play a role in weight loss. This diet requires that the total calories consumed each day should not be too high, and the high total calorie intake will lead to excess calories being stored in the body, which will not play a role in weight loss.