Perhaps they are, perhaps they aren't. But it seems to me that the way to figure out whether they are or are not is by taking the very reasonable step that they took: a visit to their GP (and including following the doctor's referral to a nutritionist).

Metabolic health is not the only type of issue overweight people face.

I suspect the real issue is that there are no universally proven ways to reduce weight that have high success rates of adherence - for example, this is why CPAP and insurance is really tricky... too many people wear them for a bit then stop using them, wasting thousands of dollars (between the sleep study and the equipment itself).