Calories in vs. calories out is the science of it.
Why obese people over eat is the psychology of it.
Obese people most often can't get over the psychology of it to be able to apply the science.
When the weather gets warmer, try walking outside as quickly as you can for a half an hour everyday and include walking up a steep hill. It's great exercise, and it will motivate you. I'll be doing the same thing.
I recently joined Curves, and I really like it. You can go at any time of the day.
Overeating, overdrinking, oversmoking.... I see it as a matter of will of power and self-discipline. In any case, people can always have a huge bowl of romain lettuce with vegetables and tuna or lean chicken with a fat-free dressing instead of Big Mac with fries. People don't end up obese when their extensive diet is based on vegetables and lean meat.