I think you missed the point.
Being overweight, BY ITSELF, is unhealthy. Being underweight, BY ITSELF, is not bad, unless you go to the extreme of malnourishment. The article points out that typically the bad part is the drug use, heavy smoking, etc.
Being underweight brings about a higher risk factor for death. Why do you try and contort the argument to be disparaging against fatties?
The facts are.
Underweight patients of all ages (those with a BMI of 18.5 or under) were found to face a 1.8 times greater risk for dying than patients with a normal BMI (between 18.5 and 25.9), the study found.
By contrast, obese patients (those with a BMI between 30 and 34.9) face a 1.2 greater risk for dying than normal-size patients. Severely obese patients -- those with a BMI of 35 or more -- faced a 1.3 times greater risk.
That's not even counting "overweight" patients of 25.9+ BMI.