To quote from "Deciding to Get Fat"
geocities.com/doctorfeeder/dtgf.html:
You like fattening food. Your favorite foods just happen to be laden with calories and you're tired of passing them up all the time. Wouldn't it fun to always order dessert when you go to a restaurant? Or even have an extra dessert? Once you've decided to get fat, you can have all the fattening goodies you want.
You like to overeat. Obviously, if you decide to get fat you can overeat as much as you want. And once you get fat, your capacity will increase, allowing you to overeat even more.
You're tired of feeling guilty. If you're trying to keep your weight down and failing, you will feel guilty over your weakness, your inability to control your appetite. But if you decide to gain, there's suddenly nothing to feel guilty about.
If you gain weight, it's not a sign of failure, it's a sign of success!
If you eat more than you planned, it's not a sign of weakness, it just means that you're getting good at this.
You hate dieting. If you decide to get fat you never have to diet again. In fact, you really shouldn't diet again. If you have the idea in your mind that you might diet at some point, it will undermine your decision to gain, and invite guilt (see previous point). There's no sense in getting fat if you're going to feel guilty about it.
Your significant other wants you to gain. This is not a good reason to gain by itself, but if you want to gain anyway, why not enjoy it?
You find it erotic. Of course, this is one of the main reasons people gain on purpose. If you feel that way, you already understand it better than I could ever explain. If you don't, you probably never will.
