What do you mean by fat?
Chub and bear are also not the same. This is a big misconception. There are many bears who don't consider or identify themselves as chub. There are many chubs who refuse to label themselves after an animal. Usually bears go to the gym and keep a healthy active lifestyle. Usually chubs don't care about their bodies or their body image. But there are chubs who consider themselves bear and vice versa. So it's complicated.
Me I'm a fem black slender twink and I'm attracted to all men of all shapes and sizes. But I understand that not all gay men think like this.
But going back, what do you mean by fat?
Are you a little pudgy and kinda stocky? Like you have a little meat on your bones but are still active and can wear regular sized clothes and walk up stairs and can run and ride a bike etc.
Then you should be fine at any gay event and you shouldn't worry.
Are you obese and large? Then you would probably have to find a chub or chub chaser group for that if you are going to meet people and to have romantic liaisons, yes I agree.