As obesity rates in the U.S. continue to climb health researchers have begun to study many different factors that can affect weight. A new study suggests, however, that there may not be enough research into how doctors can encourage already-proven methods for weight loss.

The study, published in The Journal of the American Medical Association, reviewed studies about how doctors can use behavioral treatment for obese patients. The study found only 12 high-quality studies on the issue, and no studies in which doctors followed the Centers for Medicare and Medicaid Services’ (CMS) guidelines for behavioral counseling.

“After an exhaustive search, we found only 12 high-quality randomized controlled trials that examined the behavioral treatment of obesity in patients encountered in primary care settings,” said Thomas Wadden, lead author of the study and director of the University of Pennsylvania’s Center for Weight and Eating Disorders. “Of those, only two studies identified counseling interventions that produced an average loss of at least five percent of initial body weight, an amount likely to improve weight-related health complications.”

Wadden and his colleagues found that, of the 12 studies covered in the review, those that used behavioral interventions that included a reduced-calorie diet and prescribed physical activity were generally most effective. A higher number of counseling visits within the first six months of a behavioral treatment for obesity was also found to be associated with greater weight loss.

In 2011 the CMS approved reimbursement for behavioral weight loss counseling, but only under strict guidelines that require CMS-approved primary care practicioners. The study’s authors believe that more research is needed to determine the effectiveness of these guidelines. They also suggested that remote weight loss counseling via telephone or the internet could be effective.

“I think we will see increasing use of remotely-delivered weight loss counseling, whether by telephone, smart phones, the Internet, or other digital approaches,” said Adam Tsai, a co-author of the study and an obesity specialist at Kaiser Permanente in Denver. “Telephone-delivered counseling, provided by counselors from a patient’s primary care practice, or by a trained interventionist from a disease management call center, is likely to be more convenient and less costly for patients and potentially for health care providers and insurers.”