It's more than obesity. Diet feeds your gut. Your gut biome, in turn, affects the rest of your body- including your mood, personality, and behavior, in ways you are not anticipating.

My son, if he has a single cookie, will develop raging athletes' foot and become a complete monster for days. When I say monster, I mean violent and completely uncontrollable. Maybe you don't have to deal with it, and for that you should be thankful, but for others, it's a no shit problem that they have to deal with day in and day out. Be thankful, but don't presume that your blessings are bestowed on the rest of humanity.