Excuses. Whether you are active or not, if you eat the same number of calories as you burn, then you don't put on weight. If you eat more than you burn, you get fat. Basic.
As for Bridgette's post, I understand what you're saying, but these are again excuses. Thyroid problems can be treated completely. If you can't exercise, eat less. Emotional problems are an excuse for over (or under) eating. We all have problems at times, but don't use them as a crutch for our own eating binges. Physical disabilities that prevent exercise? C'mon...look at the Special Olympics. They have overcome their disabilities. In the end, it's all excuses.
Sorry to be so blunt, but they are all excuses that are not really valid (OK, a very small minority are, but those are rare). Obesity is killing people, causing massive health issues, and it's all because people won't (not can't!!!) stop eating more than they need. If you put on weight, it's your fault, no one else's.
If you let yourself get overweight, it means you have no respect for yourself. Or the people who care about you. It's YOU, not them...