From what I have read the benefits of the short DF is to get you accustomed to doing a longer one. Apparently the best option is the 5 day and the point initially of the shorter ones is to get you to that point. There is a utilization crisis that your body has to go through where it learns how to use it's resources better. However, after the 5 days DF, the shorter 36-48hr DFs serve a similar purpose as the 5 days.
Additionally, I think if your goal is weight loss then the intermittent DF will work since the intermittent Water Fasting is reputed to work and DF is purported to be 3 times as effective.