I certainly wouldn't have guessed that they all weigh the same.
Overweight is a measure of the body weight to height and structure. Whether it can ever be an objective measurement or only subjective, I don't know. The first and third ladies are definitely overweight. Some of the others are not toned out with six-packs but are they overweight? Hmmm... possibly, but muscles weigh more than fat and skin, so if you only go by weight it's a tough call. And when standing relaxed, I've meet many people whom I first thought were out of shape only to find out it was all muscle, not fat at all. So, appearances can be deceiving, but there are definitely lots and lots of situations where it is very easy to say "overweight" or "underweight".
Plus, sometimes there is some amazing muscle and control underneath the fat. I no longer judge someone's abilities in all situations just based on how (s)he looks.