U.S. News sums up this study that shows (again) how thinness is not a measure of health.

According to the study, cardio-respiratory fitness is a greater determinant than weight when considering mortality.  In other words: you can live longer if you are fitter, no matter what your weight.

Researcher Steven N. Blair says that, "Adequate fitness can be achieved with 30 minutes of moderate exercise each day, such as brisk walking, regardless of your weight."

Is that too much to ask for improving your quality of life and extending your longevity? 

I am tired of people starving themselves thin and thinking that they look healthy.   When, in reality, they probably have the metabolism of a hibernating bear, brittle bones, and little to no musculature.

As Blair puts it, "You really can't tell if a person is fit by looking at them."