By now it's a familiar refrain: Americans need to lose weight and get fit. But the necessity couldn't be more dire, the report says, citing data showing that about two-thirds of U.S. adults — 131 million people — are overweight.

Despite the enormous public health impact of excess weight and a sedentary lifestyle — at least 300,000 premature deaths and more than $90 billion in health care costs each year — many doctors are failing to capitalize on their unique ability to help change patients' ways, the report says.

Primary-care doctors "clearly have the access, as the average American makes three office visits per year," according to the report in Monday's Archives of Internal Medicine.

Many doctors might think they do not have time during already-rushed office visits, but the new recommendations could take only three extra minutes, the authors said.

That is less time than doctors spend treating high blood pressure, high cholesterol, diabetes and heart disease — some of the major complications of being overweight, said Dr. JoAnn Manson, the report's lead author and chief of preventive medicine at Harvard's Brigham and Women's Hospital.

"We're treating the symptoms of the disease, rather than the root cause," Manson said. "We will be spending more and more of our time addressing the health consequences of obesity if we don't spend these few minutes with prevention."

The report is co-authored by Archives editor Dr. Philip Greenland, a Chicago heart specialist, who said it is designed to serve as a practical guide outlining specific steps doctors should take.

"It should not be left to the diet books and health clubs," he said. "This is really a serious medical issue and it should be conveyed to patients as a serious medical issue."

The message is directed at the journal's more than 105,000 subscribers, most of whom are internal medicine doctors who serve as primary-care physicians.

The recommendations include:

• Assessing body mass index and waist measurements and discussing patients' activity levels at every visit. Patients who are not overweight should be congratulated. Overweight patients should be told about the dangers, which include a doubling of the risk of heart disease and a tripling of the risk of diabetes for people with a body-mass index of 30 or higher, which is obese.
• Counseling overweight patients to reduce their daily food intake by 500 to 1,000 calories and get more exercise, with a goal of losing up to two pounds a week.
• Writing a prescription for exercise, such as walking a mile briskly at least five days a week. Sedentary patients also should be advised to incorporate more activity into their daily routines by doing things like using stairs instead of elevators, walking during lunch breaks or getting off the bus or subway a stop early and walking home.
• Using a pedometer, which can help motivate some patients to walk more. A good long-term goal is to take 10,000 steps daily; many people average about half that, Manson said.
• Strength training or weightlifting, to help raise metabolism.
• Weight-loss medication for obese patients who do not shed pounds after several months of cutting calories and increasing activity.
• Referrals for stomach-shrinking surgery for some severely obese patients who do not succeed with less drastic methods.