Define "use it more often". Doctors recommend diet and exercise all the time. It's the first thing to recommend to patients. It's simply very hard for people to accomplish it, and the vast majority of people either can't or won't lose weight.
I'm 42, I've been involved with two major medical systems for 30+ years, both in Canada and the United States (Kaiser) - for one reason or another, I've been to a doctor maybe a dozen times. For about 15-20 years I was either on the cusp of obesity, was always overweight - and certainly was never in the slightest bit of good physical shape.
In that 30+ years, I solemnly swear no medical official has ever made any recommendations about diet and/or exercise, with one exception of a emergency room intake doctor giving me some guidance on drinking more water after I was checked in for dehydration and the second time, when I contacted Kaiser Intake (half dead from a case of pneumonia ) - and they recommended I drink tea with a bit of honey. Sum total of diet advice.
In general, the medical system is much more interested in "Fix it when it's broken" then they are "Prevent it from breaking in the first place."
And they really tend to reach towards surgery/and drugs any time there is a problem. Some are offended when you suggest that perhaps an affliction might be diet recommended.
It's not a tin-foil-hat theory reaction. The American Journal of Clinical Nutrition has any number of peer reviewed observational studies on what happens to indigenous populations when they encountered western (refined) diets.
Taubes has an endless number of references in "Good Calories, Bad Calories" for those who are even moderately interested in how unbelievably important diet turns out to be when it comes to modern health.
But, where's the money in getting people to lead a healthy lifestyle?
People will need to figure this stuff out for themselves, it certainly won't be marketed to them the way HFCS laden beverages will be.
I'm 36, I was a physician for 8 years (no longer practicing). I recommended diet and exercise to many many patients for general prevention and certainly for anyone with type 2 diabetes. And this was considered standard of care. I was not the exception.
Doctors make standardized dietary recommendations that are not enough to protect and heal against lifestyle diseases. Compare the 30% fat American Heart Association diet to the Dr. Dean Ornish, Dr. McDougall, or Dr. Esselstyn diets that recommend 10% fat and whole foods, not products marketed as 'low fat' snacks and meals. The latter diets are clinically shown to reverse heart disease, essentially heal Type II diabetes, rheumatoid arthritis, and many other diseases. There is ongoing research by McDougall into multiple sclerosis, based on past great success with the low fat Swank diet.
The standard dietary advice is given largely because people can't make enough changes to even follow that, much less make the effort to have every single meal conform to something as seemingly 'radical' as a 10% fat diet.
So yes, arn, "doctors recommend diet and exercise all the time", but it's not to the extent necessary to bring about meaningful results.
But carry on with your dismissal of anything that doesn't make you feel good (mentally, physically, or morally) as "tin foil conspiracies". And follow the herd and make sure others can take care of you (and pay for you) when you get sick.
So you agree with me. People won't follow even a "moderate" diet. So why do you think they will follow a more stringent diet?
But (as the OP does) blaming it on a lack of financial motives does put it squarely in the conspiracy theory realm for me, as it ignores any individual responsibility and blames it on the "bad system" instead.