If you believe that your fat isn't your fault, you must also believe that you are born stupider than skinny people. Hundreds of studies show that the average obese person has an IQ significantly lower than that of the average slim person. Those who blame outside factors say that obesity isn't a person's fault.  That means that being stupid makes you fat.  You were born stupid.  So you got fat.  You will die stupid, for sure, and probably also fat.  Under this regime, the person who is fat who isn't stupid is a fluke of nature.  Smart-fat is almost a contradiction. The alternative is the realization that all kinds of people can make bad choices and end up fat, and the fat itself causes brain damage.  So being fat makes you, on average, dumber.  It still means that 1,000 fat people will have average IQs lower than 1,000 slim people because of averages.  But this means that you can be smart and fat, just less smart than you would be otherwise. There are literally millions of people willing to believe that they were born with sub-normal intelligence to relieve themselves of the responsibility for their actions. (By the way, the science is clear.  Obesity causes brain damage.  If you lose the weight young enough, it's usually reversible and doesn't lead to early dementia.  If you don't lose the weight, chances are you'll be in the first levels of dementia by 65 if you're still alive.  Congrats.)