Well, I did a 40 day fast almost a year ago and I am still here. I have had no ill effects only better health. I am starting a new Water Fast tomorrow (hopefully, I get over the hard part, the first few days of hunger) and will try again for 40 or as long as 50 days -I will go by true hunger to end fast. Fasting is not harmful, in fact today I checked my blood pressure at the pharmacy and it is the optimal/low range. I am pleased. I am doing a fast for weight loss and health purposes.