It is not strange, we slightly heavier persons have much more energy for the body to fight of external problems like virii and bacteria, besides I have seen a lot of "fit" people who are heavier and a lot of ill ones who are thin. thin == fit has more to do with fashion and culture than with health. Many people don't realize that all of us are the decendents of the wealthy and fat in the middle ages.
I totally agree - I think the biggest problem with the article is that it frames this as a “paradox.” Based on theory and what’s been observed, there is no paradox - it’s a simple fact that the common weight-health paradigm is a myth.