Trials examine lifestyle interventions for obesity

Two recent trials published May 14 by JAMA looked at the effectiveness of different lifestyle interventions for patients with obesity.

In the first, a randomized clinical trial in the United Kingdom, men with obesity were assigned to 12 months of behavioral text messages plus financial incentives (n=196), 12 months of behavioral text messages alone (n=194), or a waiting list (n=195). Enrollment took place between July 2021 and May 2022, with final follow-up in June 2023. All patients received a pedometer and weight management information at baseline. Although both intervention groups received identical text messages throughout the study, those in the financial incentive group were told that £400 (U.S. $490) had been set aside in an account for them to access at the end of the trial but that money would be lost if they didn't meet their three, six, and 12-month weight loss goals. Those on the waiting list served as the control group.

Mean patient age was 50.7 years, mean body mass index was 37.7 kg/m², and 90% were White. Seventy-three percent completed 12-month follow-up. Compared with the control group, the mean percentage weight change at 12 months was significantly greater in the group who received text messages plus financial incentives (mean difference, −3.2% [97.5% CI, −4.6% to −1.9%]; P<0.001) but not in the group who received text messaging alone (mean difference, −1.4% [97.5% CI, −2.9% to 0.0%]; P=0.05). Mean (SD) weight changes were −5.7 (7.4) kg in the text messaging plus financial incentives group, −3.0 (7.5) kg in the text messaging alone group, and −1.5 (6.6) kg in the control group, and 12-month mean (SD) percentage weight changes from baseline were −4.8% (6.1%), −2.7% (6.3%), and −1.3% (5.5%), respectively.

The researchers noted that the dropout rate was higher in the text messaging alone group than in the other two groups and that no data on weight loss are yet available past 12 months, among other limitations. "Among men with obesity, a text-messaging with an endowment financial incentive intervention significantly improved weight loss compared with a control group; however, text messaging alone was not significantly better than the control condition," they concluded. "These findings support text messaging combined with financial incentives to attain weight loss in men with obesity."

In the second trial, researchers at a U.S. medical center tested whether a wireless feedback system for weight loss was noninferior to the same system plus telephone coaching and whether participants who did not respond to initial treatment lost more weight with more versus less vigorous step-up interventions.

Four hundred adults were randomly assigned to three months of treatment with or without phone coaching between June 2017 and March 2021. Those whose weight loss was suboptimal at weeks 4 and 8 were randomized again to a modest or vigorous step-up intervention. The wireless feedback system involved a Wi-Fi-based activity tracker and scale that transmitted data to a smartphone app and provided daily feedback on participants' progress. Coaching involved 12 weekly 10- to 15-minute calls from trained nonphysicians who had access to participants' data, while step-up interventions included supportive messaging via app-based screen alerts with or without coaching or powdered meal replacement. Participants were given $20 for the three-month follow-up visit, $40 for the six-month visit, and $60 for the 12-month visit. The study's primary outcome was the between-group difference in weight change at six months, with a weight change of −2.5 kg considered the noninferiority margin.

Participants' mean age was 40.5 years, 76.3% were women, 66.5% were White, and the mean body mass index was 34.4 kg/m². One hundred ninety-nine participants were randomly assigned to the wireless system and 201 were assigned to the wireless system plus coaching. Approximately half of each group did not respond to initial therapy and were assigned to a step-up intervention. At six months, outcomes data were available for 85% of participants, with weight loss of −2.8 kg (95% CI, −3.5 to −2.0 kg) in the wireless system group and −4.8 kg (95% CI, −5.5 to −4.1 kg) in the wireless system plus coaching group. The difference was −2.0 kg, with a 90% CI of −2.9 to –1.1 kg that included the noninferiority margin. Changes in weight were similar at three and 12 months for all participants and at six months for those who did not respond to additional therapy and received step-up interventions. Results did not differ by step-up therapy.

The study required participants to have access to a smartphone and the 12-week duration was relatively brief compared to standard clinical practice, among other limitations, the authors noted. They concluded that the wireless feedback system used in their study was inferior to the same system with added coaching and that no step-up intervention was superior to another for improving weight loss among participants who did not initially respond. "Continued efforts are needed to identify strategies for weight loss management and for accurately selecting effective interventions for different individuals to achieve weight loss goals," the authors wrote.

An accompanying editorial noted that studies of obesity management tend to focus largely on behavioral interventions for weight loss despite increasing understanding of obesity as a chronic disease and that the concept of a single large-scale intervention that can work for everyone should be reevaluated. The editorialists also stressed the importance of a stepped approach and said more work needs to be done to determine which patients with obesity might be most likely to respond to low-intensity behavioral interventions.

"The idea that minimal intervention or modest education and behavioral guidance alone should be a first-line treatment for all may be a central fallacy," the editorialists wrote. "This approach risks furthering disparate treatment access, where resource-limited groups who often bear a higher burden of obesity-related morbidity will continue to receive low-cost, low-intensity behavioral support with modest benefits, while those with resources will seek and demand more intensive treatment, whether indicated or not."