Is a fat fetish normal?

Not into the fat personally, but whatever floats your boat.

Fatty lover yucky poopy fatty lover.

I'm a girl and straight so I don't relate but I think it's fine, it's also nice for girls like me who feel insecure about their size, but I don't think I'm what you're looking for.

You're what is commonly called a feeder. I feel sorry for whoever your future partner is because you are going to end up pushing them into an early grave by enabling an unhealthy weight gain.

You describe yourself as physically fit, which is a good way to be, so you should be able to comprehend just how unhealthy it is to fetishize fat. Take a good long hard look at yourself before you decide to pursue a relationship revolving around your weight gain fetish, maybe look up a documentary on feeders and eaters, it's not a glamorous lifestyle. Often the eaters end up bedridden and completely incapable of caring for themselves and solely rely on ther feeders to not only feed them, but bath them, washing between their scabby bed-sore infested rolls, and every aspect of their living.

So no, it's not normal, and I can't with good conscience recommend you pursue it. There are websites out there catered to the fetish, maybe you should sign up to one of those to satisfy your urges so you don't do real harm to an innocent person.