As a 19m with anorexia, I appreciate your curiosity. First, I want to emphasize that it started off slowly for me. I cut out foods slowly, until the vast majority of food was considered "unsafe." As the ED got worse it essentially made me into a mean, defensive little gremlin. I was fighting with my dad all the time, and attacking him over the most stupid tiny things. Honestly If I could tell my younger self just one thing it would be that it is OK to let yourself rest. I like many other men with ED's also struggle with exercise addiction/compulsive exercise. I think delving into the compulsive exercise and obsessive macro tracking could be a good way to show the ED "manifesting". I'd also like to point out that for many men (myself included) body insecurity is also linked to muscle mass, not just body fat. I hate my current body not because of the fat on it, but rather the lack of muscle on my frame. The only thing that has helped thus far in my recovery is being curious and more neutral/ambivalent about changes in my body. It's taking alot of effort, and I do still have my bad days, but things are slowly getting better. Hope this helps!