I know my answer is a bit generic, but I gained weight simply because of overeating over a long period of time. There might have been some psychological issues that attracted me to food, but I never really thought that through. I lost all the excess weight in a slow process starting in August 2011 and ending late 2016, and have kept the weight off for well over a year now -- by just counting and limiting calories, with the help of a Fitbit tracker.
__________________
********************************
Trikeman