Debatable. They clearly have enough calories, but you need more than just that to live and be healthy. I would strongly argue that omega-3's and vitamin D3 are essential nutrients that a substantial portion of the population are deficient in.
So among the group of people that are not basically falling apart from a nutrient deficit, the ones that eat about the right amount of calories tend to be (quite a lot!) healthier than the ones that eat far more or far less calories.