Basically every diet program for the last 4 years, every change to food or social habits at least in the US, failed to curb it. So in a pretty real sense we did not know how to eat less successfully, emphasis on successfully.
Yes we do. We toss out the technology and go back to substance farming or hunter/gathering. You'll have no trouble "eating less". But that requires social coordination and humans much prefer to escape society through the use of drugs. Always have, always will.
I think the revolt you'd get from trying to move everyone back to subsistence farming (and also getting conquered by some other group who didn't do this) also means we don't know how to do that successfully. You're ignoring that last word again.
Protip: Read right up to the end of the comment before pressing reply. You missed a whole lot of context by rushing to respond midway through.
What I'm saying is that "knowing how to do something" requires knowing how to actually implement that solution, how to get people to agree to do it. You might as well say "we know how to get to tau ceti".
Did you not read your own comment? It already said that before.
There is an implicit requirement of "while not making survival chances significantly lower".
Yes, mass starvation is an extremely effective weight loss technique. However, some feel there are downsides to this approach.
Is it helpful to point out solutions for problems facing society that don't apply to "humans"?