muscle milk might not keep him in keto though, if he's talking about ckd (didn't affect me when I tried it, so that might be an option)... guess I'll share Biggs' List of MRP Ingredients, might give you some ideas:
-Whey (duh)
-Egg/Casein (duh)
-PB (some people worry about the 7g carb... I don't, didn't affect me)
-Spices (cinnamon, clove)
-Extracts (rum, vanilla, almond... a dab'll do ya)
-Heavy Whippin' Cream (booya)
-Full Fat Cream Cheese (no carb, really helps make it smooth and creamy as well)