The family doctor (the famous health insurance doctor) should prescribe a diet to the severely overweight patient , regardless of the reasons why the latter has turned to him, perhaps wasting 30 more seconds explaining the reasons why a weight loss diet it’s necessary. 
A provocative exit, that of the researchers of Oxford University, who analyzed the relationship of almost two thousand obese subjects with their doctor: half of them were convinced by the doctors (it took thirty seconds more on the reasons why it was necessary for them to lose weight) to take part in a weight loss program ( Slimming world, which does not exist in Italy: think of something like Weight Watchers); the other half simply received advice to lose weight to improve their health.

But as I had already explained to you in this article , it is not enough for the doctor to tell the patient that he must lose weight : this advice alone could trigger a series of mechanisms in the patient by which any diet is fine, the important thing is to decrease.
But no. The doctor must offer solutions that are inexpensive (or free) and that help the patient lose weight in health. 
Wasting a little more time with your patients would help reduce the case of people relying on DIY or the internet to lose weight.