Examining overweight patients also involves looking at two factors besides weight: one is metabolic risk, which refers to illnesses like type 2 diabetes, high blood pressure, and high cholesterol. The other is fat mass consequences, which are basically all the mechanical realities that come with gaining a bunch of weight (joint pain, sleep apnea, acid reflux, etc.). Basically, is a person so fat that it hurts their knees to walk, or prevents them from falling asleep? If neither of those issues is present, it’s safe to assume a patient is relatively healthy, despite his or her weight.
The opposite can also be true; someone who looks perfectly healthy and of an average weight externally could have serious metabolic complications raging on the inside. Other lifestyle factors play a major role in overall health as well, most of which you learned about before high school, like smoking, drug addiction, stress, and lack of sleep, to name a few.