Background: Behavior programs can help patients lose weight, but maintaining weight loss remains a challenge. Most studies of dietary interventions are of relatively short duration, so reliable evidence for effective weight loss maintenance is lacking. Weight loss maintenance strategies are important because lower body weight is associated with fewer cardiovascular risk factors. Black patients are disproportionately affected by obesity, and are especially at risk of obesity-related cardiovascular disease. Svetkey and colleagues conducted a 30-month controlled trial comparing two types of active weight maintenance intervention with a self-directed control.
The Study: The Weight Loss Maintenance trial consisted of two phases. Inclusion criteria for phase 1 were a body mass index between 25 and 45 kg per m2, an absence of active cardiovascular disease, adherence to antihypertensive or cholesterol-lowering medications, access to a telephone or the Internet, and keeping a five-day food diary during screening. Exclusion criteria were diabetes requiring medication, weight loss greater than 9 kg (19.8 lb) during the three months preceding the screening, use of weight loss agents, or previous weight loss surgery. The entry criterion for phase 2 was 4 kg (8.8 lb) weight loss during phase 1. Participant data were collected at the beginning and end of phase 1, and every six months after randomization until the study’s conclusion at 30 months. Measurements included height, weight, dietary intake, and physical activity.
After the six-month structured weight loss program in phase 1, eligible participants were randomized to a self-directed weight maintenance control group or to one of two active interventions: an interactive technology-based weight maintenance program or a personal-contact intervention. The content of the active interventions was similar, but the process for each was distinct. The first was an Internet-based program, and the second combined telephone contact with face-to-face visits. Both approaches implemented continuous, regular contact, self-monitoring approaches, and motivation. The primary outcome was change in weight from randomization to the end of the study.
Results: Of the 1,685 phase 1 participants, 1,032 (61 percent) were eligible for phase 2 of the study. At the study’s end, energy intake decreased in all groups, but did not significantly differ between groups. The amount of physical exercise in all groups reverted to pre-study levels. Weight regain was 5.5 kg (12.1 lb) in the self-directed group, 5.2 kg (11.5 lb) in the interactive technology-based group, and 4.0 kg in the personal-contact group. Compared with the self-directed group, the personal-contact group regained 1.5 kg (3.3 lb) less weight (95% confidence interval [CI], 2.4 to 0.6 kg; P = .001), and the interactive technology-based group regained 0.3 kg (0.7 lb) less weight (95% CI, 1.2 to 0.6 kg; P = .51) at 30 months. More than 70 percent of randomized participants remained at or below their entry weight, and 41.8 percent of participants maintained a weight loss of at least 4 kg. The proportion of those maintaining this weight loss was highest in the personal-contact group, followed by the interactive technology-based group and the self-directed group. All differences were statistically significant.
Conclusion: The personal-contact group had significantly less weight regain than the interactive technology-based or the self-directed groups. The mean effect was only 1.5 kg, but it occurred across all demographic subgroups. Even this small difference is likely to have some clinical impact because of the cardiovascular benefits resulting from reduced weight. The technology-based group also had significantly higher weight loss maintenance than the control group, so this type of intervention should be a priority for research and continued development.