One of the problems with obesity is that we live in a country (I can only speak for this one) that fetishises
eating the fattiest, butteriest, richest dougnuttiest foodstuffs. We treat it like those are the only food pleasures and that lettuce and fruit and water is garbage.
We also woefully under educate people on what proper diet is (I get it it should be self explanatory).
Example: my co-worker is currently on a ketogenic diet (of which I am a proponent) and I had to explain multiple times as to what items he couldn't eat (mainly all the things he usually does).
On the other hand, we celebrate the thin and pretty so if you can't be one (thin & pretty), you might as well have the other (fat and ostensibly happy).
Finally I think the health services industry also under-serves us in that we get so little time with our doctors (we can't all have on call concierge health professionals, some of us are lucky to get 15 minutes with a NP once a year) that the best (most) they can (are willing to) do is tell us "you're fat" and then it's "see you in 12 months". I don't think people even know what 1200 calories looks like.