I suspect that here in "The West" with our immense choices and support, with food that comes from all over the world, with transportation networks that can get all that food into your kitchen within days of processing, any diet could be healthy.
But if you don't have all that infrastructure and support, if your region is overrun by locusts or warlords or gangs, then sticking to any "I'm only going to eat these categories" diet is impossible. You eat what you can get, and if you don't happen to have enough plant food today, eating meat (if available) is healthier than starving.
But if you don't have all that infrastructure and support, if your region is overrun by locusts or warlords or gangs, then sticking to any "I'm only going to eat these categories" diet is impossible. You eat what you can get, and if you don't happen to have enough plant food today, eating meat (if available) is healthier than starving.