Yes, maybe a lack of effort or unhealthy choices but Why? Why would someone choose to be fat and/or unhealthy
Wrong question, being asked of the wrong people. IMO.
Relatively few people choose to be fat and unhealthy. Ditto black of lung and unhealthy. Ditto constantly chastised and living in a sea of rampant disorganisation/procrastination. Ditto bleeding of finger tip with a gob full of finger nail.
What we choose (IMO) is the avoidance of the discomforting, painful, marathon-esque nature of breaking & changing habits. And the avoidance of the utter fucking itchy slog of sticking to new behaviours that resist becoming habits... so you end up spending far too much of daily life being intentional to be properly comfortable. Which is knackering on its own, even before you plonk the gnawing "I'm missing what I am denying myself" on top.
And the reason there's no point looking outward for answers is because the only person who can dump avoidance and fairly bad temperedly, and not exactly consistently in my case choose the frustrating, itchy slog of change, rather than the feather bed of "what I have been doing for quite a long time", is the person who is unhappy with the status quo caused by their behaviours.
Note- (us = people unhappy with status quo caused by their behaviours... but are not exactly jumping for joy at the prospect of uncomfortable/painful change)
Looking outwards leaves us wide open to the siren song of those who would tell us we are powerless and doomed to failure. It's a seductive message because ...
it waggles the avoidance of uncomfortable/painful change as the only sane option
AND
tells us we have limited responsibility, this is something that has happened to us. Not something we are doing to ourselves
AND
reframes every other bugger who does not fall into line (patting our heads and saying "poor you" and "anyway you are perfect as you are"), who instead insist we do have a choice, we do have the power to make changes and we do have some responsibility for our status quo .... as monstrous bigots. Not quite on a par with members of the KKK and The Eugenics Fan Club, but definitely somewhere up high on the scale of GitFaced Prejudiced JudgeyKnickered Bastards. Which kind of helps mute their message nicely. Being as they are oh so immoral and all that jazz.
Once the siren song has done its job, there is often a worsening of the status quo that was causing unhappiness, because the little self control being employed previously is dropped in the excitement of "It's not me, it's THEM ! Let's talk some more about how awful THEY are and how I am both amazingly strong/powerful AND a helpless victim ... all at the same time"
Looking outwards for an answer to the wrong question carries a heightened risk of humans like me i.e.
rather flawed
prone to avoiding things I don't enjoy (especially changing of habits and mindset)
devoid of Will Power Of Steel That Kicks In On Demand And Self Maintains Its Throttle qualities
prone to maintaining a vice-like grip on "stuff I like"
capable of generating inordinate amounts of self pity if it will help me achieve my "avoiding things I REALLY don't like" objective
....to a life that can become less about living, and uncomfortably close to a form of slow, drawn out suicide.
IMO & IME