It’s not just calories in calories out. Obesity is very complex and includes some environmental factors we have very little control over. It seems some people like to believe that every fat person is just a glutton, but that is just not the case! This is a nice little video that attempts to explain some of the many factors involved.
I’ve also written quite a lot about psychiatric drugs and fat, since the increased use of psych drugs, too, is an additional factor in people getting fat these days. Often people are made to believe it’s their fault they’re getting fat when sometimes there is very little one can do as long as they are on the offending medications.
Gut health is also important as he ends the video. People with healthy gut flora are likely to be thinner. He suggests fecal transplants! Since that is not easily available as of yet, there are ways to improve gut health via diet. And I’ve written a lot about that too: