My brother actually noticed on our trip last weekend to see our mother that I had lost weight (shocking - he is not a very observant type). So I explained to him about 5:2 and the benefits of IF. He said he might want to try fasting (our mother has dementia - certainly a motivation for IF).
But he is quite thin - BMI probably between 18 and 19. So clearly he shouldn't do anything that might cause weight loss.
What would be the best approach for him? I don't really think 16:8 is an intense enough fast to be useful with anything beyond the obvious (helps with weight loss because you won't eat as much in 8 hours as you would in 12 or 14). I've been doing 16:8 frequently over the years without thinking of it as a weight loss strategy - without even thinking about it at all, actually. I just wake up late sometimes and only eat two meals.
@Carorees, maybe there are some studies or articles for me to send to my bro?
PS Why didn't I get those genes? My dad used to graze all day long. He would complain sometimes after a meal that he ate too much. And he was thin as a rail, as they say.