There is no official explanation for the obesity crisis except people are lazy and eat poorly. The only alternative to this is that officials are ignoring other explanations. This, in most people's minds, is conspiracy theory to even suggest and that's what makes people uncomfortable.

Most people don't know how to answer questions outside their limited domain expertise without relying on authority figures. Telling them their authority figures are unreliable on such an important topic seriously complicates their lives.

I think that it is fairly well acknowledged that obesity, both in the US and globally, has gotten a lot worse fairly recently.

There's a lot of different theories, and a lot of controversy as to why but the idea that wide scale obesity is a fairly recent problem is not controversial.

I'd guess that the reason why the top comment here was downvoted, if it was downvoted, is that many people feel it's an obvious problem; calories in and calories out and the falling costs of calories in and the increasing cost of calories out explains the whole thing for me. You take an organism that has lived essentially on the edge of starvation for hundreds of thousands of years, and you put it in an environment where calories in are almost free and where for most of them, calories out are not? and yeah, those organisms are going to overeat. (Just my opinion, but it's a common one)

(the complaints about downvotes were downvoted because they are complaints about downvotes; those are obligatory downvotes.)

As a meta point, I've found people over the past few years less willing to even entertain facts that contradict their worldview. I blame the culture war, which has broken, in a serious way, the ability for lots of people to think critically and evaluate arguments on their own. People instead interpret posts that don't confirm their conclusions as attacks on their person, and then downvote, block, and counterattack as needed.