Let's kick this off with THE TRUTHS about how challenging it is to keep lost pounds, just that, lost. It’s a tough job, in fact tougher than taking off those unwanted pounds in the first place.
Research shows that the most weight people lose, even with pretty constant expert support, is about 6 to 10% from your starting weight. Example: 200 pounds that's 12 to 20 pounds. Doesn’t sound like much compared to those triple digit losses touted on Biggest Loser or from for-profit diet plans. Research also shows people lose these pounds by about 6 months to 1 year max. It’s simply tough to lose more weight. For sure there are exceptions. Read Weight Loss, Control: Expectations vs. Research-based Realities.