How the hell did I manage to do this years ago?

I used to eat 3600 calories, 180 grams of protein a day in addition to all my soda. Looking back now idk how I did it. I barely got half that today and feel like Im gonna burst my stomachs so full. I think it’s because of the low cortisol crap but if I even think of a protein drink I start to gag. I could barely eat a meal and a protein bar today and I continue to only be able to drink juice and soda. How the hell do bodybuilders manage it? I mean besides the fact they take steroids.