A full answer to your first why is a mystery. But a related question is a lot more tractable because you can ask fat individuals: how can you stand being fat? F

A full answer to your first why is a mystery. But a related question is a lot more tractable because you can ask fat individuals: how can you stand being fat? For a lot of fat people (and I invite you to look at a BMI height/weight chart to see what counts in analysis as fat/obese), they're like "yeah" about it because that's the extent it seems to affect their daily life. That is, in the experience of a typical fat person, getting their BMI under 30 (if obese) or under 25 (if merely "overweight") would not actually be a "huge" benefit to them. Being fat and even obese doesn't actually preclude a lot of fat people from doing the things they want to do. Even from a pure health perspective, the relative risks of being fat often top out at like 2x for the most fat and specific health issues. The relative risk for dementia from this submission's study is only 1.177x. (Smoking, in contrast, finds relative risks for lung cancers > 20x.) But if the base rate is low, even 2x of that rate is still fairly low, and not necessarily enough to care about making a potentially difficult life change over. Getting into the "severely obese" category (BMI > 40) I think is where day-to-day issues become more common, though that's "only" about 9% of the US adult population.