You doctor may know very little about managing obesity or nutrition. I’d ask a registered dietician or a health coach instead. 5:42

Statistics Canada says more than half all adult Canadians are either overweight or obese. They can use some helpful tips on how to eat healthy. But experts in obesity say your doctor may not have the best advice.

We don't know about the advice provided in privacy of a doctor patient relationship. What we do know comes from studies in which doctors are quizzed on their knowledge of nutrition. In a study of medical school graduates entering residency to become paediatricians, they were tested on an 18-point nutrition questionnaire. The average mark was just 52 per cent. Other studies have documented that on average, the knowledge doctors have about obesity and how to manage it is out of date.

The problem is that physicians not being taught the latest concepts in medical school. A study published in the journal Academic Medicine found that in the 2008-2009 academic year, just 27 per cent of 105 medical schools met the minimum requirement of 25 hours of teaching on nutrition. A more recent study found the number of med schools keeping up with obesity and nutrition education has gone down. Medical schools aren't teaching enough about nutrition, and the people who make up licensing exams aren't testing that knowledge. A panel of experts on obesity looked at the content of medical licensing exams; it found that the most important topics on obesity aren't well tested on the exams.

Sodas and most other sugar-sweetened drinks sold in California would be required to carry warning labels for obesity, diabetes and tooth decay under a bill introduced in Sacramento and backed by several public health advocacy groups. REUTERS/Sam Hodgson (Sam Hodgson/Reuters) Short of up to date teaching many doctors fall back on myths and misconceptions about obesity. Many believe obesity is caused by too many calories and not enough exercise. They ignore other contributors such as psychological stress, hormonal factors, medications and lack of sleep. They don't know that the Canadian Obesity Network endorses improving sleep for weight management. A second misconception is that people with high BMI are less active. The Canadian Health Measures Survey says just 7 per cent of Canadian children and youth and 15 per cent of Canadian adults are active physically. If activity were that important, you'd expect a much higher percentage of non-obese Canadians to be physically active. Many doctors believe diets work, even though 2/3 of people who lose weight regain it within 1 year. Many MDs still believe weight loss is a matter of willpower. People with obesity have tremendous will power. Most doctors still think fat causes disease. The trouble isn't with fat; it's with sugar.

The knowledge and testing gap is important because rates of obesity have risen over the past generation. Obesity is a risk factor for diabetes, heart attacks and strokes, depression, osteoarthritis, and even cancer. We're seeing these diseases at younger and younger ages. As physicians, we act as if we're overburdened treating patients with all these kinds of diseases. We're supposed to be in the business of preventing disease or minimizing its impact. By not addressing these issues, I think we're missing in action on one of our most important tasks.

Some medical schools are improving education of medical students and residents. As welcome as that is, I don't think it provides better access to the latest information quickly enough to the patients who need it.

Registered dietitians are the ones I'd ask. They have the requisite knowledge and experience to do the job. I also favour using health coaches to teach patients what they need to know about nutrition and about obesity – provided they're trained by RDs. Health coaches partner with patients to teach them and to set specific and achievable goals for health.

Health coaches are available in some family practices under pilot programs. New Brunswick provides them free of charge to people with diabetes. That program has helped people in that province to lose weight, eat better, with lower blood pressure and better diabetes control. Elsewhere in Canada, health coaches may be covered by extended or employee benefits, and you can pay for them out of pocket.

I think RDs and health coaches make enough of a difference that the system should pay for them. The investment would be well worth it.