> we do know that diet and exercise work.

Stricly speaking we don't.

This is "common sense" and the official recommendation, but fundamentally we don't have solid long term reproductible experiments[0], and due to the nature of the problem (humans living their life in a complex society) we'll probably never have a good answer.

I've read many many studies spanning a few months and calling it a day (did the subjects rebound ? who knows), other taking a very small and homogenic pathological group, making it follow a strict regimen and end the experiment right after the subjects are let free again. But nothing with an actually rigorous protocol that gives a clear undisputable result.

In a way I feel a lot of researchers are bound to their common sense and think they either don't need to prove the obvious, or it brings them nothing to let the room for controversial results ? (nobody's paying for research that says current policy is dumb)

[0] If you have any double blind study with more than a hundred subjects taken randomly from the general population (including "healthy" subjects), with a control group, spanning more than 3 years of observations I'd be dying to read it..

If you think that's a high bar, obesity is touted to be the worst health crisis the US has to deal with with tremendous impacts, putting at least that much effort into research doesn't seem outlandish.

> But we do know that diet and exercise work.

Sure - if you ignore the incredibly poor % of people who comply with a prescription of diet and exercise. If you include compliance then the drugs are way way way ahead.

We know for sure that obesity is one of the single biggest increases in all-cause mortality. We know it is directly linked to most of the top disease-related causes of death.

> But we do know that diet and exercise work.

Do you think the ~40% of American adults that are obese don't know that they should eat better and exercise more? That they don't understand that they're cutting decades off their life?

Yes, it is 100% within the power of the overwhelming majority of them to fix things. And I think evolution has kept shame with us for a purpose and that it can be a useful emotion. But I also think it's plainly apparent that neither are causing a real reduction in obesity.

So, should all the people in the world that are obese just continue to fail at losing weight despite knowing what they should, in theory, be doing to resolve it? Because, despite being obese being one of the riskiest things you can do in life for your health and lifespan, we don't know if there might maybe be long term effects from something we know will get them to lose weight?

This room is on fire! I could run out that door over there - I know if I open it and go through I'll leave this room that is currently on fire - but, should I? What if whatever is on the other side of the door is just as bad as being on fire, or worse?!