It's a multifactoral thing, gut flora has an influential effect on brain chemicals, those influence your behaivour...if you take depression as a result of chemical imbalance, what do you go do, cheer yourself up on food in the short term, weight gain ensues...and you can't exactly deal with the weight gain until you address what's influencing the behavior that puts the food in the mouth. But if you were to 80/20 it, I doubt fatfucks are depressed because of gut flora issues and more because they're simply rejects.