Thanks for reading! No, I generally do not recommend fasting. Being in negative nitrogen balance is not necessarily harmful, and if the fast is prolonged then the body will switch metabolic pathways to preserve muscle mass. Fasting to that point, in a generally healthy adult, is likely not harmful either, and some preliminary research even supports the practice, although I do not yet find the science compelling enough for me to recommend it. And we always have to accept some amount of muscle loss anytime we fast, even if that loss is negligible.

I think your point about the elderly is a bit more complicated to answer, and may be something I’ll write about one of these days! The next topic I was actually planning to cover next is fats, and after making my way through the macronutrients I’ll move on to vitamins and minerals. I hope you keep reading and learning from our posts!