I'm not the guy you are replying to, but most MDs really don't know anything about nutrition. That simply is not a topic they ever took a class in, and official nutrition recommendations themselves are completely changing. The "food pyramid" with a base of carbs? Must eat breakfast of sugary cereals and orange juice? That's all murderous nonsense. (And it's changed!) And so on.
MDs want "stable" patients who resemble patients they've familiar with. Even though that could mean being diabetic on half-a-dozen meds. Based on my genes, I would be fat and diabetic by now if I had kept following only my doctor's advice.