Prepackaged, portion controlled, protein calories are the best way to lose weight. Cottage cheese and Greek yogurt calories are on the package. Canned chicken and canned tuna calories are on the tin. You need 75-120 grams of protein a day, depending on your age, sex, health and activity level. Predigested liquid protein contains 15 grams of protein in 60 calories. Protein contains 4 calories per gram. Lean animal protein generally contains 5 or 6 calories per gram, when you add in the fat. Try to limit your protein calories to 500-600 a day. If you can’t do 500-600, try 700-800. If you can’t do 700-800, bump it up to 1000. If you go much over 1000 protein calories a day, you probably won’t lose weight fast enough to stay on your diet.