People always underestimate the endocrine system. Your frontal cortex and everything that you are is basically just a tool for your endocrine system to use to get food and sex.
It's why eating less is so hard for some people. If the endocrine system is being pushy, it can just make you not care about your goal, and not many people can do something uncomfortable that they don't want to do in furtherance of a goal they don't care about.

Healthy, stable eating habits need to come before weight loss eating habits, and that needs to be paired with light excercise as you build up.
Like taming a wild animal. Some people just have a capybara, and others have some sort of ocelot that's addicted to meth. Most people have dogs. Gotta ease in, but once you get started it's fine as long as you don't traumatize the poor beastie.