A lifestyle intervention combining diet and physical activity resulted in significant weight loss and improved cardiovascular risk factors after 12 months in a study of 101 severely obese adults. The results were published online Oct. 9 in JAMA.
Few clinical trials have focused on the effectiveness of diet and exercise interventions for the severely obese, said Bret H. Goodpaster, Ph.D., of the University of Pittsburgh and his colleagues.
In this study, 130 severely obese adults were randomized to the diet and exercise intervention for 12 months or dietary intervention only for the first 6 months with physical activity added after 6 months. Of these, 101 completed the 12-month study (JAMA 2010 Oct. 9 [doi:10.1001/jama.2010.1505]).
Both groups lost significant weight after 6 months, but those in the group that started exercising immediately lost significantly more weight on average in the first 6 months than did those in the delayed-exercise group (10.9 kg vs. 8.2 kg, respectively). The immediate-exercise group maintained their average weight loss advantage at 1 year, although the difference in weight loss between the two groups was no longer significant (12.1 kg vs. 9.9 kg, respectively).
In addition, participants in both groups showed significant improvement in blood pressure and insulin resistance, as well as reductions in waist circumference, visceral abdominal fat, and hepatic fat content after 12 months, compared with baseline levels. However, the hepatic fat content loss was significantly greater in the immediate exercise group, compared with the delayed exercise group after 12 months, the researchers noted. No differences in adverse events were reported between the two groups.
The participants were prescribed a weight-loss diet based on their initial body weight, and they received low-cost exercise supplies, including pedometers and exercise videos. During the first 6 months, participants had one individual meeting and three group meetings each month. In the next 6 months, they had two group meetings and two telephone calls per month. Participants who met their weight-loss goals were eligible for periodic small financial incentives.
The participants were aged 30-55 years, more than 80% were women, and 37% were black. A total of 98 patients (75%) had a body mass index of 40 kg/m2 or greater (class III obesity), and the remaining 25% had a BMI between 35 and 39.9 (class II obesity).
Patients with uncontrolled hypertension or diabetes, as well as those with a history of cancer, bariatric surgery, or participation in a formal weight-loss program were excluded. Women who had been pregnant during the past 6 months or individuals being treated for coronary artery disease also were excluded.
A total of 78% of individuals in the immediate activity group lost more than 5% of their baseline body weight after 12 months, compared with 65% in the delayed activity group. Regardless of intervention group, the class III obesity patients lost significantly more of their body weight than did the class II patients after 12 months (10.9% vs. 7.0%), the researchers noted.
The results reflect findings from similar studies in overweight and class I obese individuals, the researchers said. “In addition, despite the slightly lower weight loss in African Americans, the interventions were effective in white as well as African American individuals,” they added.
“Although this lifestyle intervention did not achieve the degree of weight loss typically observed following bariatric surgery, this magnitude of weight loss was associated with significant improvements in insulin resistance, blood pressure, and levels of plasma triglycerides,” the researchers noted. “Our data make a strong case that serious consideration should be given by health care systems to incorporating more intensive lifestyle interventions similar to those used in our study.” However, more research is needed to determine cost-effectiveness and long-term efficacy, they said.
The study was funded by the Commonwealth of Pennsylvania Department of Health. Dr. Goodpaster had no financial conflicts. Study coauthor John M. Jakicic, Ph.D., reported serving on the scientific advisory board for Free and Clear (an organization that specializes in Internet- and Web-based cognitive behavioral coaching), serving as a consultant to Proctor & Gamble, BodyMedia (a weight-loss system), and the University of Pittsburgh Medical Center Health Plan. Dr. Jakicic also reported receiving research support from BodyMedia and the Beverage Institute for Health & Wellness.
Dr. Ryan disclosed having received compensation from NutriSystem and from companies that develop weight-loss medications, but reported that she has not received any compensation from “the weight-loss sector” since January 2008. Dr. Kushner disclosed receiving compensation from the weight-loss service Diet.com and companies developing weight-loss medications.