Oct. 11, 2010 (San Diego) -- Calorie restriction and physical activity can help overweight, obese, and even severely obese people lose weight, according to new research presented at the annual meeting of the Obesity Society.

"These interventions can work," researcher Bret H. Goodpaster, PhD, of the University of Pittsburgh, told meeting participants. "They don't always work, but they can work."

Goodpaster says he isn't suggesting that lifestyle interventions can replace weight loss surgery, but simply that they shouldn't be ruled out as an effective strategy.

In another study presented at the meeting, overweight and obese women enrolled in a structured commercial weight loss program, Jenny Craig, lost more weight than those not in the program, says researcher Cheryl L. Rock, PhD, RD, a professor of family and preventive medicine at the University of California, San Diego.

"It works," Rock tells WebMD. "No drugs, no devices, no surgery."

Both studies were published online Saturday in TheJournal of the American Medical Association.

The research drew praise and caveats, with some experts saying the findings are cause for optimism and others saying the structured program results represent a ''best-case" scenario.

Slideshow: Frighteningly Fattening Fall Foods
Lifestyle Interventions for Severe Obesity: What Works?

More than 14% of U.S. adults are severely obese, with a body mass index (BMI) of 35 or more. But just 1% of severely obese patients get bariatric surgery each year, according to Goodpaster.

While many experts view lifestyle approaches as ineffective for the severely obese, little research has yet been done, according to Goodpaster.

In the study, Goodpaster assigned 130 severely obese adults with an average age of 46 and all with a BMI of 35 or above into two groups. Both groups were told to reduce fat and calories and given liquid and prepackaged meal replacements for free, with meal replacements tapering off as the study progressed. Small financial rewards were given for reaching goals. Support was given in group and individual meetings and by phone.

One group began exercising at the start by walking briskly five days a week, working up to 60 minutes a session. The second group began to exercise at the six-month mark.

At six months, weight loss in the group that began diet and exercise at the start was about 6 pounds higher -- 24 pounds compared to 18. But the delayed exercise group caught up.

After 12 months, 101 participants remained.  "At 12 months there were no significant differences between groups in weight loss," Goodpaster says. The diet and exercise group lost about 27 pounds, while the delayed exercise group lost 22. The average BMI declined from about 44 to 39.

Both groups also had reductions in waist circumference and abdominal fat. They had improvement in insulin resistance, reducing their diabetes risk, he found.

Commercial Weight Loss Programs

In the second study, Rock randomly assigned 442 women who were overweight or obese to one of three groups:

    * A group of 167 women was enrolled in a center-based commercial weight loss program.
    * A second group of 164 women was assigned to a telephone-based commercial weight loss program.
    * A third group with 111 women was assigned to a ''usual care" group which served as a comparison group.

Those in the comparison group received a consultation with a dietary professional who gave them diet and activity guidelines and meal plans. They had a one-hour educational session, then a monthly check-in by email or phone.

The others were given prepackaged foods free of charge plus all the features of the program, and $25 for each clinic visit. The program studied was the Jenny Craig program. Rock served on the advisory board for Jenny Craig from 2003-2004 but was not on the board when the study began. Jenny Craig supported the study, and University of California, San Diego funded it as a clinical trial.

The women's average age was about 44. BMIs ranged from 25 (barely overweight) to 40 (severely obese).

At 24 months, the study showed:

    * Women in the center-based program lost 16 pounds.
    * Women in the telephone-based program lost 14 pounds.
    * Women in the usual care group lost 4.5 pounds.

"The telephone and the center group had no [substantial] difference in weight loss," Rock tells WebMD.

After 24 months, both groups in the commercial program had lost about 7% of their initial weight, she says. "They clearly learned behavior and strategies. Something stuck."

The commercial plan won out, Rock suspects, due to many of its components. "Structured meal plans are helpful for people," she says, as they take the guesswork out of how much people are supposed to cut back.

The personal contact is also useful, she says. Participants could address barriers to weight loss -- such as how to eat out and stay with the plan -- as they came up and get guidance.

''If you change your lifestyle not in an extreme way or risky way you can lose weight and keep it off for at least two years," Rock says.
'Best-Case Scenario'

''This shows some good hope," says dietitian Eileen Myers, RD, of the new findings. For doctors, the message is not to decide on an obesity treatment just based on the BMI, she says.

The personal contacts and frequency of contact with the program administrators are probably key, she says.

In an editorial accompanying the new research, Rena R. Wing, PhD, a long-time weight control researcher at Brown University, writes that the findings on the Jenny Craig program ''probably represent a best-case scenario"  because of factors such as free food.

Even so, she suggests such weight loss programs need more research and that providing them free of charge might be ''a worthwhile health care investment."