Are you attracted to the big girls or are you just desperate to get laid or get a girlfriend?
I unfortunately know a little bit about this so I can speak from experience.
I don't know to many dudes that are chubby chasers but if you are, more power to you, it's your life. Personally, I think the vast majority of the time when a guy is going after a fat chick, he's desperate. It's either one of the following scenarios:
1. He can't do any better. His breath smells of rotting skunk carcass and he hasn't showered in a week so that's the best he can do. If you want an example, just look at the Jerry Springer rejects.
2. He thinks he can't do any better. This is due to inner game issues or limiting beliefs.
3. Desperation. You're so desperate to be in a relationship so you'll take anything. If it's not a fat chick, maybe you're taking on a crack addict or psycho. This is because you're desperate.
4. It's easy. Fat chicks require little work and almost no game whatsoever. There's also very little competition. They're just grateful to have you around. Attractive women require more work.
Whenever I've gone after fat chicks in the past, it was one of those above reasons. Same thing with people I know. I had a fat girlfriend for a while a few years ago and it was unbelievably easy. It took no work at all to pull her or keep her around. Still though, you'll hate yourself for settling and you'll find yourself not attracted to her in the process. There was another time when I called over this fat chick who must have weighed 250 pounds because I was so desperate for pu$$y and it was easy. I ended up hating myself in the process and I couldn't go through with it, not to mention the whole physical attraction factor.
Personally, I'd rather beat my meat than go that route again. Don't settle.