It's because you succeed by committing to a lifelong set of healthy habits.  When you lose weight through surgery, crash diets, pills stimulants, and over-exercising, you're going to gain it all back because you never adopted a healthy sustainable lifestyle to begin with.  That's the story in one way or another with most of these massive weight loss stories.  Instead of aiming for a slow steady loss of about 1-2 pounds per week through a manageable and reasonably small caloric deficit combined with moderate exercise, fat people are impatient and take massive shortcuts which end up hurting them in the long run. Successful long term weight loss is about patience, something which fat people are severely lacking.  They want their quick fixes and instant gratifications.  But more than that, it's about commitment to a healthy lifestyle for the rest of your life, otherwise known as being a responsible adult.  And since fat people are essentially children, this is something that most of them will never do.