What? This isn't suggested or taught in any high school curriculum I know of. Not only that but it is technically true and most people who actually diet do more research than "starve yourself" because who is too lazy to do research but not too lazy to make a huge lifestyle change and constantly exert control over their purchasing/prep/eating habits? Decades for the body to recover? I mean, if you literally starve yourself to near death to the point where you cause organ damage you might never fully recover I guess, but seriously, nobody is doing that without already having severe issues beforehand. The overarching suggestion of "eat less calories if you want to be less fat" is effective and non-harmful advice as the majority of people who remain overweight tend to overeat. Which is unhealthy and can take decades for the human body to recover.