For the vast majority of people fasting is not the best way to lose weight and keep it off (although there are always exceptions). Still fasting can be a very valuable adjunct to a safe, sane weight loss diet. Fasting cleanses the body at a deeper level than either diet alone or even single organ cleanses. The cleaner the body becomes, the easier it is for it to assimilate nutrients from less food. This helps the body shed excess pounds faster without compromising health and nutrition.
I really believe that one day a week fasting should be a part of a weight loss plan. Three days a month and, eventually, ten days one to four times a year will help keep the body cleansed as long a a clean diet is maintained most of the time.
I do strongly believe in Water Fasting for health, healing and cleansing; however lengthy Water Fasts will rarely prove the best method of permanent weight loss.