Fasting for 30 days plus is perfectly healthy if done right. Most of us faced enough body far stores to feed our bodies that long. Once your body starts metabolizing the stored body fat your blood sugar will balanced out, and in most cases your cholesterol wool drop to normal levels too. It is important to keep using your body, read exercising during the process or you will loses muscle. A buddy of mine would do this for 30-40 days at a time, with his Dr. monitoring everything weekly. They checked blood suffers, cholesterol, muscle mass every week. He did both juice and water fasts that way. The longest I went was 30 days.