If you are over weight you need to detox. That is fundamental. The question is, what is the safest method. That is always the question with every practice or diet. If you are overweight, have no symptoms or diagnoses of illness, your best bet is to ETL. You will lose weight and give yourself a first class education in nutrition as well as establish the HABIT of eating correctly.
Fuhrman, while Vegan, does allow for some meat and dairy for those who feel they can't make it without those foods. He also knows that some will follow 60%, others 70%, etc. of his advice and every little bit helps. He does not preach or demand, but the evidence is so overwhelming that one feels motivated to follow the correct practices.
Even if you are ill, a few weeks on the ETL diet is recommended before a water fast, unless the illness is so severe you need immediate treatment. Then Fuhrman would have you go into one of the many fasting clinics around the country to be supervised (he does not profit from them, except his own clinic).
In Fuhrman's first book (1995) he comes close to recommending fasting for weight loss. In his current book (2003) he has changed his position a bit. Apparently
Water Fasting is used as a healing modality or infrequent rejuvenator. His wife has fasted only once, and for a very few days and enjoys excellent health. Fuhrman has only fasted once, many years ago, for over 40 days. His experience is that if one eat's correctly a fast of 10-15 days every 5 or 10 years or so for rejuvenation is all that's needed. However, he does recommend a fast of 1-3 days during colds and acute infections if one desires.
I like to fast one day a week. Fuhrman does not explicitly say he disagrees with this practice, but he does disagree with 2 or more days a week, or a week per month schedule. Bragg has found 1 day a week, and 7-10 days 3 times a year to be beneficial for him and his clientele. There are Cronies (Calorie Restriction Optimal Nutrition) that fast as often as every other day. But they are experimenting on themselves ala Roy Walfords et.al. research on longevity. Not a lot of fun and only a few people are able to do that. They hope to live disease free past 120 years. This is also based on extensive testing from microbes to mammals.
Both recommendations for food for maintenance are about the same for Fuhrman and Bragg. Bragg has been a highly respected teacher, Doctor of Naturopathy, Ph.D. and licensed Physical Therapist for decades until his death, I believe in his 90's, due to an accident while surfing.