SAN DIEGO — Women enrolled in a home environment–focused weight loss program for overweight adults had greater weight loss at 18 months, compared with men, results from a randomized study showed.
“We know that behavioral interventions for obesity produce sizeable and clinically meaningful initial weight losses,” Melissa Crane said at the meeting “But because changes in eating and exercise behaviors are rarely maintained over time, we see a weight regain within the first 3-5 years post intervention. One reason perhaps is that the intervention focuses almost entirely on the individual, largely ignoring the context in which eating and exercise behaviors occur.”
Ms. Crane, a research assistant in the Comprehensive Cancer Center at the University of North Carolina, Chapel Hill, went on to note that most 6-month weight loss programs consist of two educational sessions: one on stimulus control and one on how to increase social support for weight loss. “Otherwise, they're largely expected to implement their new knowledge and skills within their existing environments,” she said. “Failing to modify environmental cues and temptations may make it very difficult to establish new behaviors and make the changes necessary to produce long-term weight loss.”
For the study, known as the Lifestyle Eating and Activity Program (LEAP), 210 overweight and obese adults were randomly assigned to standard behavior treatment alone (standard treatment group) or standard behavior treatment plus direct manipulation of the physical and social home environment (home group). Both groups received 18 months of treatment: 6 months weekly and 12 months biweekly. Treatment goals included a diet of 1,200-1,800 calories per day, with 30% or less of the calories from fat, plus gradually increasing exercise to 200 minutes per week of moderate intensity exercise. All study participants were taught behavioral techniques including self-monitoring, problem solving, goal setting, cognitive restructuring, and relapse prevention.
Goals for the home group included modifying the type and portion sizes of foods consumed in the home, modifying the availability of exercise equipment and sedentary activities in the home, increasing the saliency of the consequences of food choices, and creating a positive model for healthy eating and exercise in the home.
“During the screening program, all participants were required to identify a partner within their home who was also overweight and willing to participate in the program,” Ms. Crane added. “For participants randomized to the home group, those partners were encouraged to attend all group sessions and were required to set a weight loss goal and make similar changes in eating and exercise. In the standard treatment group, the partner attended the weight loss 101 session and assessments only.”
Study outcomes were assessed at baseline, 6 months, and 18 months with a combination of clinic and home visits. Weight loss was the primary outcome. Secondary outcomes included results on home environment measures, including the Home Food Inventory; the Exercise Environment Questionnaire; the presence of aerobic equipment such as a treadmill and whether it was stored in a visible, usable space; the number of televisions in the house; and the Sallis Social Support Questionnaires.
Ms. Crane, who discussed the study on behalf of lead investigator Amy Gorin, Ph.D., of the psychology department at the University of Connecticut, Hartford, reported that the mean age of participants at baseline was 49 years, 78% were women, and 82% were white. Their mean body weight was 99 kg and their mean body mass index was 36 kg/m
At 6 months, the home group lost significantly more weight, compared with the standard treatment group (a mean of 9 vs. 7 kg, respectively). However, by 18 months the difference in weight loss between the two groups was no longer significant (7 vs. 5 kg).
The researchers found that gender was an important moderator of treatment outcome. For example, women in the home group lost significantly more weight than did women in the standard treatment group (a mean of 7 vs. 4 kg, respectively), whereas men in the standard treatment group lost significantly more weight than did men in the home group (a mean of 14 kg vs. 8 kg, respectively).
At 18 months, partners, regardless of sex, lost significantly more weight in the home group than in the standard treatment group (a mean of 7 vs. 2 kg, respectively).
One possible explanation why the home group lost more weight than the standard treatment group at 6 months but not at 18 months is that the modifications to the home environment “may not have been sustained over time,” Ms. Crane said. “For example, when we look at changes in the home food environment, we see that between baseline and 6 months, participants in the home group showed greater increases in low-fat items available, smaller decreases in fruits and vegetables present, and greater decreases in high-fat spreads. But by 18 months the home environments looked remarkably similar between the two groups.”