GIP

GIP-mediated calorie sensitivity is an underappreciated reason why total caloric load during a fast affects autophagy depth. GIP triggers an insulin spike every time food passes through the small intestine, regardless of the type of food. Any meal triggers GIP in the small intestine, which amplifies insulin — meaning overall calorie load matters for autophagy, not just carbohydrate content. Gastric bypass surgery works by physically bypassing the small intestine and eliminating GIP activity, not by restricting caloric intake. Gastric bypass is effective for both weight loss and type 2 diabetes because it eliminates a major insulin trigger, not because it reduces food quantity. Even dietary fat can trigger a GIP response, so avoiding carbohydrates alone is insufficient to preserve autophagy.