Prescription weight-loss drugs can help consumers shed a moderate amount of weight when combined with a dieting regimen, a new study finds.

And a second study by the same RAND Health researchers found that for the severely obese, weight-loss surgery produces better results than exercise and diet alone.

Both studies appear in the April 5 issue of the Annals of Internal Medicine.

In the review of the most popular weight-loss drugs, the researchers examined studies of orlistat (Xenical); sibutramine (Meridia); fluoxetine (Prozac); bupropion (Wellbutrin); topiramate (Topamax); sertraline (Zoloft); zonisamide (Zonegran); phentermine; and diethylpropion.

They concluded that most of the drugs can produce modest weight loss when combined with dietary recommendations. The amount of weight lost on each drug varied. But the researchers concluded that the loss attributed to the medicines was slightly less than 11 pounds at the one-year mark.

“Sibutramine, orlistat, phentermine, probably diethylpropion, bupropion, probably fluoxetine, and topiramate promote modest weight loss when given along with recommendations for diet,” the researchers wrote.

For the surgery review, the researchers analyzed the results of nearly 150 studies on weight-loss procedures.

The most common surgery, gastric bypass, typically produced a weight loss 20 pounds greater than another common procedure, vertical-banded gastroplasty.

The bottom line is that “surgery is better than non-surgical therapy at weight loss and controlling some of the obesity-related conditions like Diabetes and high blood pressure for certain obese individuals,” said Dr. Paul Shekelle. He is senior author of both papers and acting division chief of general medicine at the Greater Los Angeles Veterans Healthcare System and a health scientist at RAND Health, a health policy research institute in Santa Monica, Calif.

The finding lends more credibility to the idea that surgery should be considered as an option for certain people - particularly those who have a body mass index of 40 or above, for whom diet and prescription weight loss medicines have not proven satisfactory, and are willing to take the risks of surgery. A BMI of 40 or above is termed severe obesity. A 5-foot, 7-inch person who weighs 260 has a BMI of 40.

The severely obese patients who underwent weight loss surgery typically lost between 45 and 65 pounds and maintained that lower weight for 10 years or longer, the analysis found.

The study conclusions reflect advice in new guidelines released this week by the American College of Physicians for obesity management. The ACP guidelines recommend that people with a BMI over 30 consider drug therapy and that surgery be reserved for those with BMIs over 40 who also have obesity-related health problems, such as high blood pressure, Diabetes or sleep apnea.

The RAND researchers looked at four surgical procedures: the Roux-en-Y gastric bypass in which the size of the stomach is decreased; vertical banded gastroplasty, in which bands and staples are used to reduce the capacity of the stomach; adjustable gastric band or Lap Band, in which the stomach size is reduced by a band; and biliopancreatic diversion, in which the stomach is made smaller and food bypasses some of the small intestine.

They found that about 20 percent of those who undergo obesity surgery have complications. While most are minor, some are not, such as intestinal leaks, which can require more surgery. The death rate was less than 1 percent, the study found.

The message for consumers, said Dr. Melinda Maggard, general surgeon at the UCLA David Geffen School of Medicine and another study co-author, is that “using surgery for weight loss is a reasonable approach, especially for patients who are severely obese. But it’s not without risks and it’s not a quick fix.”

The new studies will provide sound guidance to physicians, said another obesity expert, Dr. Frank Greenway, professor and chief of the outpatient clinic at Pennington Biomedical Research Center, in Baton Rouge, La.

“RAND Corporation is very well respected,” he said. “When they do these studies they do them very well.”

Greenway said the research shows that weight-loss drugs should provide an 11-pound or so average loss over a placebo, and that surgery gives you much more, but should be reserved for those with BMIs over 40.

In his work with obese patients, Greenway reminds them that even with weight loss after drug therapy, they are probably not going to get to a “normal” weight. But they will probably have health benefits from even a modest weight loss. “People who have obesity surgery tend to be cosmetically pleased,” as well, he said.

To calculate your BMI, visit the Body Mass Index (BMI) Page.

SOURCES: Melinda Maggard, M.D., general surgeon, UCLA David Geffen School of Medicine, Los Angeles; Paul Shekelle, M.D., acting division chief, general medicine, Greater Los Angeles Veterans Affairs Healthcare System and health scientist, RAND Health, Santa Monica, Calif.; Frank Greenway, M.D., professor and chief, outpatient clinic, Pennington Biomedical Research Center, Baton Rouge, La.; April 5, 2005, Annals of Internal Medicine