I know diet is important all day but if he is using a short acting slin then he needs to be most aware of is carb intake after the slin right? So if he is going to do it I hope he researches the proper carb intake for the type of slin he is using. Hypo can come on fast. Sorry if I missed it did he give a reason why he wants to use it?
What I'm having a hard time finding is how people use slin to diet. I know you can use it to bring yourself into keto quickly, but people use it throughout their diet with a moderate amount of carbs. I'm assuming you use just enough to keep blood levels low enough to stay in keto, but high enough to still fuel the muscles.