In what is the largest and longest study of weight loss programmes, Duke University researchers have found that personal contact helps.
"The results of this study send a strong signal to those who seem to believe that obesity is such an intractable problem that nothing can be done about it," said Laura Svetkey, co-author of the study.
"A large majority of the participants kept weight off for two and one-half years," she noted, adding that counselling was a great help in keeping the inches off.
Findings of the study have appeared in the latest issue of the Journal of the American Medical Association.
Svetkey and researchers at four institutions around the country studied 1,685 overweight adults who were being treated for high blood pressure, high cholesterol, or both.
Scientists asked them to increase their activity level, reduce their calorie intake and follow the DASH diet (Dietary Approaches to Stop Hypertension) for a period of six months.
The DASH diet emphasises fruits, vegetables, low-fat dairy products and whole grains, and has been proven to lower "bad" cholesterol and blood pressure.
In the first phase of the study, participants attended 20 weekly group meetings with a trained interventionist who coached them on making these lifestyle changes.
Only participants who lost at least nine pounds were admitted to a second phase of the study; 61 percent met that goal. In the second phase, 1,032 participants were randomised to one of three groups.
A self-directed control group were left to their own devices to manage their weight. A personal contact group received monthly coaching and support from a counsellor assigned to them.
A third group received a computer-based, weight loss maintenance programme which offered the same counselling that personal contact offered, but in a virtual, interactive format.
More than 70 per cent of the participants weighed less at the end of the study than when they started.
But those in the personal contact group were the most successful, with 77 per cent maintaining some weight loss. The computer intervention group had a 69 per cent success rate and the self-directed group had 67 per cent.