I've had this IRL discussion too many times, where the non-veg person says that a lack of meat affects their sleep, energy level, digestion, etc. I'm not a dickhead, and I don't argue with people's lived experience, even if it feels very sus.
I've done a good faith search for evidence of how certain people might have negative health effects from not eating meat, and nothing turns up. (Short of just having a bad veg diet) Maybe I'm missing something. It's just frustrating how often people use this as an excuse, and they're often anti-vegan in their wider ideology.
I mean for the gastro stuff I pointed out it's valid, there's sadly people that experience a similar reaction to galactans (from beans) that people do to lactose (also similarly sets off IBS), there's also brassica and cruciforms that set off IBS (though green beans and spinach are low FODMOP alternatives, funny enough red and processed meats are also big trigger for IBS as well). These are specific conditions and not baseline as stated before and so likely is not what is claimed by individuals that state that meats are superior to a vegan diet or that going without meat is harmful to people (it's not as long as you meet your micro and macro nutrient requirements which is easy enough in a majority situations).