There is compelling evidence, from what I read online anecdotally and some studies, of obese or formerly-obese people having much slower metabolism (BMRs and TDEEs) than predicted by regression equations when controlling for body composition and weight. When someone says that “I’m barely eating and can’t lose weight” it is actually possible this may be the case. it's not just a failure to track calories when the tests show these people have slow metabolisms.

Basically, their bodies run in a sort of hoarding or efficiency mode, which although advantageous during famine, does predispose to obesity during abundance. These people got a bad genetic hand. They have to cut to absurdly low calories, and maintain it forever, to just not be obese or overweight.

The study has not been replicated and has few subjects.