How is leptin involved with yo-yo dieting?

Leptin is the cause of yo-yo dieting. Leptin is designed to replenish the body’s store of fat after a period of deprivation. In evolutionary times, this was a survival necessity. In modern days, this is the genetic response to a low-calorie diet. The only way to avoid having this problem is to eat in such a way as to not upset leptin balance.