In both studies, patients lost an average of more than 10 pounds after two years. That modest amount, experts said, can be enough to prevent the development of serious health conditions such as diabetes.
And by relying heavily on lower-paid "coaches" with limited training, both programs likely cost less than a doctor's time would. A big unanswered question, however, is whether insurers would pay for any of it.
Although some commercial programs like Weight Watchers are effective, only the most highly motivated people sign up on their own.
"When patients are told by their doctor that they need to lose weight, it is a much more important source of authority," said Morgan Downey, a longtime health-care advocate and publisher of downeyobesityreport.com. Plus, he said, the doctor may also be treating various conditions, from asthma to back pain, that are exacerbated by obesity. "So the message there is that losing weight is not just a good virtue in itself but is related to making better the condition that we are treating today," he said.
Even if a doctor makes a referral to a commercial program, many patients never show up, said Thomas Wadden, lead author of the Penn study.
His program was based in physicians' offices. At the end of an appointment, the doctor can say, "I want you to walk down the hall and see our medical assistant," Wadden said, "and I might capture you and get you started right then and there."
Wadden, director of the Center for Weight and Eating Disorders at Penn's Perelman School of Medicine, presented the findings at an American Heart Association conference in Orlando, Fla., on Monday; the Hopkins research was presented Tuesday. Both were simultaneously published online in the New England Journal of Medicine.
Previous studies have shown that 50 percent of primary-care physicians don't even raise the issue of weight loss with patients who clearly would benefit.
"Up until this point, if you were an obese patient and went to your doctor, there was no proven strategy for you to lose weight," said Lawrence J. Appel, a primary-care internist in Baltimore. Appel said he would discuss diet with his patients, help them set goals, and sometimes encourage them to enroll in independent programs, with mixed results.
"The office environment is incredibly hectic," he said. He thought weekly contact as well as additional outside support might make a difference.
To test that idea, Appel, also a professor of medicine at Hopkins and lead author of that study, randomly divided 415 obese patients from six primary-care practices into three groups.
Members of one group received little guidance other than a standard booklet and whatever meetings with their physicians they would have normally scheduled over the two years.
Members of the second group also had access to an interactive website that allowed them to track diet and exercise. Their doctors encouraged them to participate in 20-minute sessions with coaches - weekly in the beginning, then monthly, then every other month - by e-mail or phone. They also got feedback via weekly automated e-mails.
Members of the third group got the website, automated feedback, and coaching - but for them, the counseling was face to face, in 90-minute group sessions plus optional individual sessions. It also was more frequent - at least twice a month for two years.
To the researchers' surprise, the remotely coached group did just as well as the in-person group - losses of 10 pounds vs. 11 pounds, an insignificant difference. (The group that got minimal help lost two pounds.)
The Penn study also enrolled about 400 patients with body-mass indexes over 30 - the definition of obese - from six primary-care practices for two years and assigned them to three groups.
One group got nutrition handouts and pedometers and had quarterly visits with their doctors, who spent five to seven minutes each time reviewing their weight and discussing the handouts.
The second group's members also met monthly with a medical assistant in the office who had six to eight hours of training as a coach and worked with them to track diet and exercise.
The third group did all of the above and also had to choose either of two possible "enhancements." One was a meal-replacement bar or shake such as Slim-Fast (for two daily meals plus a snack during the first four months and one meal and a snack for the last 20 months). The other was a weight-loss drug (orlistat or sibutramine, although the latter was removed from the market partway through the study and those patients switched over).
This study's surprise was that the patients who got the least help still dropped an average of nearly four pounds. Just the minimal guidance was "more care than usual," said Wadden, a professor of psychology, and "they may have been motivated to impress their doctor."
The coached group members lost an average of six pounds. The coach-plus-meal replacement or drug group lost 10 pounds, or an average of nearly 5 percent of their initial weight, the only amount that was considered clinically meaningful. Risk factors for cardiovascular disease also improved.
"What really sets these two studies apart is that it extends the reach of treatment" beyond specialized clinics, said Gary D. Foster, director of Temple University's Center for Obesity Research and Education, who was not involved with either one. Primary-care doctors are used to treating diabetes and high cholesterol, he said, but "you can't write a script for obesity."
Still, he and others said, the scientific findings do not address a big bureaucratic barrier: Insurers typically pay little or nothing for doctors to treat obesity with counseling or drugs, and have only recently added some coverage for weight-loss surgery.
There are some signs of change. Medicare for the first time has proposed covering up to a year of behavioral counseling in primary-care settings. But the final rule, due in two weeks, is unlikely to allow payments for coaching online or by people without advanced degrees.
"I think it is a step in the right direction," said Karen Grothe, a psychologist who treats obese patients at the Mayo Clinic in Rochester, Minn., and had cited earlier research by Wadden in a public comment that urged the government to adopt a more expansive rule.
It was a medical assistant's coaching at West Chester Family Practice that Lee Ann Richardson-Stewart credited with helping her lose 51 pounds, far more than most patients in the Penn study.
"She wanted me to be successful," said Richardson-Stewart, 53, who made myriad small changes in diet and exercise, and got off her cholesterol drug less than a year into the study. More than a year after it ended, she said, she has gained back only five pounds and now weighs 145.
Her knees no longer hurt.
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Contact staff writer Don Sapatkin at 215-854-2617 or firstname.lastname@example.org.