If he doesn't lift, then he's definitely going to be skinny. Why do you deny human nutrition facts so often? lol
Not saying it's better, since keto is hard to deal with and f**king sucks for digestion sometimes, but he's more or less correct. Our bodies don't NEED carbs to function, it just makes things a lot easier if we do have them....and there are health benefits to restricting carbs big time like that, though from a weightlifting perspective it makes things VERY difficult I find.