There is no evidence that fasting starvation does more than lowers blood lippits. Extreme caloric restriction for most people is simply not sustainable. Doctors who treat obesity have agreed that you can only go so far with somebody who has been obese to a by diet and exercise. There's something else that keeps causing them to bounce back. A former student of mine as a made some important discoveries that a fasting, mimicking diet, really only a couple of days a month, improves blood chemistry.