I want to eat, but if I do, I'll get fat.
My attempt at a translation:食べたいけどそれをすると太る.
I expect this is totally unnatural. Even if it is okay I fear that adding それを may make it sound quite formal, but leaving it out just seems totally weird.
Is there a natural way to express this "if I do" part that doesn't repeat the previous verb? If not, is it natural in Japanese to just repeat the verb? This would be a bit clumsy in English.