The where do you get your protein stories keep appearing over and over. In addition food "manufacturers" are in the current craze of stuffing protein into everything. I remembered a story from some years ago about zoo gorillas dying of heart disease and I dug up one of those stories. It seems zoos were big on feeding gorillas what amounted to high sugar and highly processed refined grain chips/cookies loaded with vitamins, minerals and protein. Unfortunately, they started dying of heart disease at an early age. One zoo decided to turn things around and started feeding their gorillas greens and vegetables and got rid of the highly processed monkey food. Those two gorillas ate twice their previous calories yet each dropped 65 pounds by the end of that year. Here is one write up about that process. I'm sure you can find even better written stories about this experiment.
https://www.sciencedaily.com/releases/2011/02/110217091130.htm