1. In a group of young-adults (18-35 year olds) with a BMI between 21 and 30, self-regulation strategies with small corrective changes in diet and activity, with or without an initial weight loss strategy, led to reduced long-term weight gain compared to a control group.
2. The study shows that meticulously following dietary and exercise plans can feasibly prevent weight gain in young-adults, and thus prevent long-term obesity-related adverse outcomes.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Weight gain amongst young adults has significant adverse health risks. Strategies to prevent weight gain during young adulthood (ages 18-35) may be beneficial to improve lifelong outcomes in health. The Study of Novel Approaches to Weight Gain Prevention (SNAP) trial sought to evaluate the long-term effectiveness of strategies for self-regulation to prevent long-term weight gain in this population. The approaches evaluated a “small changes” strategy which included corrective changes to increase activity and decrease caloric intake for a deficit of 100 kcal/day if above target weight. The “large changes” strategy included the same interventions in addition to an initial 2.3-4.5 kg weight loss through intense dietary changes during the first 4 months of the study to buffer against weight gain. There was also a third, control group.
The results of the study showed that, at three years of follow up, showed that both the intervention groups effectively prevented against baseline weight gain compared to the control group. Compared to the control group, the intervention groups had lower incidence of obesity at the end of the study. The strength of the study was the study design, large sample size, and a long follow up period. The weaknesses of the study included predominance of females, high motivation of participants, and close follow-up afforded to the participants would not be feasible for the population at large.
In-Depth [randomized controlled trial]: This trial recruited 599 participants who were motivated to prevent weight gain. The participants were 22% male, 25% racial minority, aged 18-35 years and had starting BMI of 21.0 to 30.9. Individuals were randomized to the control arm, the small-changes arm, or the large-changes arm. The large-changes group had an initial 2.3-4.5 kg weight loss during the first 4 months. Both intervention groups underwent group meetings to learn about self-regulation of activity and caloric intake in response to daily weight measurements and were taught to make changes with regards to diet and exercise as a negative feedback if weight was above baseline.
The mean [SE] weight change at 3 years for the study groups were +0.26 [0.22] kg for the control group, -0.56 [0.22] kg for the small-changes group, and -2.37 [0.22] kg) for large-changes group. Differences between groups were significant: small-changes vs. control p = 0.02, large-changes vs. control p < 0.001, and large-changes vs. small-changes p < 0.001. There was a smaller proportion of individuals who gained more then 0.45 kg above baseline amongst the large-changes (23.6%) group compared to the small changes (32.5%, p = 0.02), and control group (40.8%, p < 0.001). The incidence of obesity was also less in the small-changes (7.9%, p = 0.002) and large-changes (8.6%, p = 0.02) groups compared to the control group (16.9%). There were no significant differences related to sex, age, ethnic background, or baseline weight.
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