FRIDAY, Feb. 8 (HealthDay News) -- Doctors' beliefs about the causes of obesity can affect the advice they give to patients, researchers say.

In an Internet survey of 500 primary-care doctors in the United States, participants were asked their opinions about the causes of obesity and about what type of advice they gave to their obese patients.

The investigators found that doctors who believe that over-eating is a major cause of obesity were much more likely to advise patients to change their eating habits by reducing portion sizes, avoiding high-calorie ingredients when cooking and drinking fewer sugar-sweetened beverages.

Similarly, doctors who believe that sugar-sweetened beverages are a leading contributor to obesity were much more likely to tell patients to cut back their consumption of those beverages.

"Eighty-six percent of primary-care physicians indicated that overconsumption of food is a very important cause of obesity, followed by 62 percent of physicians reporting that restaurant or fast-food eating is a very important cause and 60 percent attributing consuming sugar-sweetened beverages as a very important cause," study lead author Sara Bleich, an associate professor in the health policy and management department at Johns Hopkins Bloomberg School of Public Health, in Baltimore, said in a university news release.

Only a few of the doctors said they believed that genetics, family history or metabolic problems were important causes of obesity, according to the study, which was published in the February issue of the journal Preventive Medicine.

Improved education for doctors about the causes of obesity may be a good way to increase the amount of nutritional counseling they give their patients, Bleich suggested. This education should include practical dietary tips that doctors can easily share with patients.

More information

The U.S. Centers for Disease Control and Prevention has more about the causes and consequences of obesity.