A study in Wednesday's Journal of the American Medical Association shows that leptin, a hormone found naturally in the body can help control appetite.
Researchers speculate those who lack the hormone, because of a rare genetic defect, are more likely to be affected by this treatment.
Obese patients were given were injections of the hormone for six months and were asked to follow a weight loss diet.
Two-thirds of the patients lost weight and a few of them had very significant reductions in weight. The higher the dose of leptin, the more weight was lost. The group that received the highest doses of leptin lost an average of 15 pounds, compared to the group that got a placebo and lost just three pounds.
Almost all of the weight lost was in fat, not muscle or bone, and no serious side effects were noted. But, since not all the patients responded to the leptin injections a much larger trial is now under way to look for ways to tell who will lose weight and who won't.
"This is not a pancea," Dr. Senay says. "It is the beginning of ways to help people lose weight."
The rate of obesity among Americans has surged in the past decade and health officials say a national campaign is needed to control the epidemic, reports CBS News Correspondent Elizabeth Kaledin.
Additional studies in JAMA show obesity now affects nearly one in five adults, killing some 300,000 people a year.
Younger adults, people with some college education and Hispanics showed the most drastic increases, but "a steady increase was observed in all states; in both sexes; across age groups, races, educational levels; and occurred regardless of smoking status," concluded a study by the U.S. Centers for Disease Control and Prevention.
Overall, the population of obese men and women increased from 12 percent in 1991 to 17.9 percent last year, according to the CDC survey, which said that figure might be conservative.
The figures were adjusted for sex, age and whether the subjects smoked but did not factor in chronic disease or family histories that might indicate a predisposition to an illness.
An editorial accompanying JAMA's obesity issue says a national campaign should focus on better health habits to prevent obesity.
Growth in the marketing of fast food and snack food, a reduction in physical education and more television watching are among the reasons Americans are taking in more calories than they burn, the editorial concluded.