Popular Diets: What Docs Eat, What They Need to Know

When doctors advise their patients about weight loss, they can have positive effects on patients' dietary and exercise habits. Research has shown that physicians with healthy exercise and eating habits are more likely to discuss exercise and weight loss with their patients.^[1,2] The Medscape Physician Lifestyle Report 2014^[3] revealed both good and bad eating habits among physicians. This is a snapshot of what more than 31,000 US doctors surveyed told us about their own diets, plus what they need to know about the diets that they and their patients are choosing.

Do Physicians Eat the Way They Tell Their Patients to Eat?
When we asked physicians to tell us which diets they routinely choose, 62% of normal- to underweight physicians (but only 39% of those who are overweight or obese) indicated diets that align with recommendations for healthy amounts of fruits, vegetables, grains, and fat. Even worse, almost half (44%) of physicians who reported that they were overweight to obese told us that they routinely choose either "meals on-the-go" or a typical American diet (meat most days; carbs most days from white rice, potatoes, or white flour products; high fat) compared with only 28% of healthier-weight physicians. Surprisingly, only 16% in the obese and overweight groups were on weight-loss or calorie-restriction diets. What does the evidence tell us about the many varying diets our readers are following?

What Do Most Americans Eat?
Although the US Department of Agriculture recommends a diet that is rich in fruits, vegetables, and whole-grain-based foods, with relatively modest proportions of fats, sweets, meats, and dairy products, the 2014 Medscape Physician Lifestyle Report found that the typical American diet (defined as meat most days; carbs most days from white rice, potatoes, or white flour products; high fat) was by far the most popular choice among physicians. The good news is that Americans — including physicians — may be turning a corner towards healthier eating. Compared with 2005-2006, Americans today are eating 78 fewer calories a day, primarily because we are eating more meals at home vs away from home. We are also consuming diets with fewer calories from total fat (3.3% less), saturated fat (5.9% less), and cholesterol (7.9% less). Fiber intake has increased by 1.2 grams per day (7.5% more).^[4]

The AHA Diet
About 24% of normal- or underweight physicians and 16% of overweight or obese physicians indicated that they follow the American Heart Association diet, making it the second most popular among physicians in the 2014 Lifestyle survey. Backed by the American Heart Association and the American College of Cardiology,^[5] this approach is as much lifestyle as diet, encouraging a host of healthy habits, including daily vigorous exercise, no smoking, and moderate (if any) alcohol intake, in addition to emphasizing a variety of highly nutritious foods and avoidance of empty-calorie foods. This approach is supported by substantial evidence linking higher levels of aerobic physical activity to lower rates of cardiovascular and other chronic diseases, probably related to reductions in lipid and lipoprotein levels, blood pressure, and type 2 diabetes.^[5]

Is the Mediterranean Diet Effective?
Roughly 21% of normal- or underweight physicians and 14% of overweight or obese physicians choose the Mediterranean diet. Similar to AHA's Heart Healthy Lifestyle approach, the Mediterranean diet is lifestyle-based, encouraging a variety of highly nutritious, plant-based foods, whole grains, fish, and poultry; red meat no more than once per month; and daily physical activity. The Mediterranean diet lifestyle also emphasizes the social importance of mealtimes by encouraging eating with family and friends. This diet is backed by substantial research linking it to reductions in cardiovascular, cardiometabolic, neurologic, and neoplastic disease, leading to improved survival.^[6-9]

The "Caveman Diet"
According to our survey, approximately 6% of overweight physicians and 8% of normal- or underweight physicians adhere to the Paleo diet. This diet is based on eating whole foods from the food groups that hunter-gatherers would have thrived on during the Paleolithic era. These include fresh, lean meats such as grass-fed or free-range beef, pork, lamb, and poultry; fish and seafood; fresh fruits and vegetables; seeds and nuts; and healthful oils (olive, coconut, avocado, macadamia, walnut, flaxseed).^[10] Dairy products, cereals, legumes, refined sugars, and processed foods are excluded. Several small studies show reductions in weight, cholesterol, and triglyceride levels, as well as improved glucose tolerance, in the short term.^[11-18] Anecdotal claims of reversals in autoimmune diseases, cancers, and other disorders await study.

Vegetarian and Variations
The 2014 lifestyle survey found that 7% of normal- or underweight physicians and 3% of overweight physicians consider themselves lacto-ovo vegetarians. Strict adherence prohibits consumption of any animal flesh, including fish and seafood. A variety of studies have shown that vegetarian diets reduce the incidence of cancer, diabetes, rheumatoid arthritis, hypertension, and heart disease.^[19-22] On the other hand, people who adhere to this diet run the risk of vitamin B₁₂ and omega-3 fatty acid deficiencies, and should take supplements for these and other deficiencies related to lack of animal proteins.^[23]

A Vegan Way of Life
In our survey, about 1% of overweight physicians and 2% of normal- or underweight physicians reported that they are vegan. As much philosophy as diet, vegans do not ingest animal flesh or animal products of any kind (cow's milk, eggs, butter, honey) and also avoid cosmetics tested on animals, food additives such as gelatin, and clothing made of leather, fur, wool, down, or silk. Studies looking at the benefits of vegetarian diets found that individuals assigned to a vegan diet for the duration of a clinical trial achieved the greatest risk reductions for all-cause mortality and type 2 diabetes.^[21,22] Although vegans can take in plenty of protein from beans and grains, they should give special attention to including ample sources of calcium, iodine, iron, omega-3 fatty acids, vitamin B₁₂, vitamin D, and zinc, or add supplements to address these potential deficiencies.^[23]

A Diet Without Gluten
Roughly 1% of overweight physicians and 2% of normal- or underweight physicians in the 2014 survey said they follow a gluten-free diet. This diet is essential for the estimated 2 million Americans who may have celiac disease, an inflammatory disorder with an autoimmune component. The diet also has become popular in people who do not have celiac disease, and there are many anecdotal claims of benefit. Recent studies identified other gluten-related disorders, including nonceliac gluten sensitivity, gluten ataxia, and wheat allergies.^[24,25] Celiac disease has a strong association with autoimmune conditions, and some research has proposed a link between gluten sensitivity and autoimmune thyroid disease, multiple sclerosis, type 1 diabetes, and rheumatoid arthritis. This diet is expensive and not easy to follow; it requires a close reading of food labels because gluten is a component of many additives and fillers. Moreover, gluten-free grains may be contaminated by gluten-containing grains during processing.

What Is an Ornish Diet?
As with vegan and gluten-free diets, only a small minority (about 1% of overweight or obese physicians and 2% of normal- or underweight physicians) claim the Ornish diet as their nutrition regimen of choice. Dean Ornish based this spectrum of lifestyle changes on 35 years of scientific research, and has shown that the program works for losing weight; lowering cholesterol and blood pressure; helping to prevent or treat diabetes, heart disease, cancer, and other conditions; and improving psychological well-being.^[26-32] As with most of the other successful dietary plans, this one also emphasizes the importance of regular exercise. The diet limits consumption of red meat to small portions no more than once monthly, and of lean poultry to no more than once daily (if that), but it allows up to 2 servings daily of egg whites and fish. Ideally, the diet comprises 10% fat, 20% protein, and 70% carbohydrates, proportions that may be difficult to sustain over the long term.

Dietary Approaches to Stop Hypertension
The DASH Diet (Dietary Approaches to Stop Hypertension) was not included in the 2014 Physician Lifestyle survey. It was originally developed by the National Heart, Lung, and Blood Institute as a nonpharmacologic strategy to lower blood pressure. The DASH diet stresses reducing sodium intake while eating more fruits, vegetables, and whole grains. Although somewhat similar to the Ornish diet, the DASH diet allows slightly more fats (primarily unsaturated), which may make it easier to follow. The diet lowers blood pressure and cholesterol levels^[33] and has the potential to prevent type 2 diabetes.^[34] Earlier this year it was ranked best overall diet by US News and World Report.^[35]