As someone who has been broke, it's pretty crazy to start think of food intake in terms of price per calorie. I need more food than the average human, as I am

As someone who has been broke, it's pretty crazy to start think of food intake in terms of price per calorie. I need more food than the average human, as I am 6'5" / 196cm tall. For a few years, I'd drink a lot of skim milk to get protein. I could get 2 quarts (1.9L) for about $2.99 USD, which contained something like 60 or 70 grams of protein. There weren't many sources cheaper than that, except for larger volumes that were hard for me to acquire & store.