I too have a rather harsh opinion of the AMA (and medical community in general) but I don't believe that they have malicious intentions to keep the majority of us unhealthy so that they can run up our medical bills. No, I can't imagine doctors wanting to do that. However, I think that they are in CYA mode on this whole issue of nutrition and basically stuck in a web of lies that they can't easily extricate themselves from.
Consider that they have been pushing that damned food pyramid upon us for decades now with its 7-9 servings of grains (or whatever the number is) per day. They can't very easily come out now and say "Gee, we had it wrong all these years. Eating lots of grains and carbohydrates is bad for you. Using concentrated corn syrup as a sweetener isn't such a hot idea after all. And by the way, hydrogenated vegetable oil isn't very good either, better switch from that margarine we've been telling you to eat all these years to butter."
If they did that, all hell would break loose. There would be a feeding frenzy (pardon the pun) of the likes you have never seen before. Thousands of lawsuits would be filed overnight. Malpractice lawsuits too against individual doctors of obese patients and/or those with Type II diabetes.
The medical community can't afford to open themselves up legally and financially like this. So it is in their interest to leak the news out slowly. Already, we are seeing studies showing that low-carb diets are effective in curing obesity and controlling medical conditions such as high blood pressure and diabetes. Yet they are not giving such studies big publicity. Yet. Then, years from now, when it finally dawns on the masses that low-carb is the way to go, they can always pull a Bill Clinton and say "Low-carb diets? Oh, that's old news. We were talking about this years ago. Here are some of the studies we did back then to prove it..."
Food Pyramid Guide by the National Agricultural Library
6-11 Servings of grains?? Then they wonder why kids are overweight.