USA the Apothecary
Doctors are NOT trained in nutrition. They learn about it on the fly, much of what they "know" has no basis in science.
There are protocols for treatment that doctors are supposed to apply. This should protect the public and mean that where ever you go to see a doctor, you will always get professional care, real medicine.
But perhaps today we've gone too far. Few doctors today will prescribe "food," because that would not be "professional."
For obesity, the doctors of today seem to know less now than was common knowledge in 1900. Dr William Osler demonstrates that. Only after WWII did obesity become a complex and difficult problem.
With regards to Type II diabetes, as Professor Timothy Noakes explains, the same fundamentally wrong dietary advice given to his father thirty years ago is still being taught in universities.