Objectives

To compare two self-regulation interventions versus control in reducing weight gain in young adults over an average follow-up of 3 years.

Background

Weight gain occurs commonly throughout adulthood and has been associated with many adverse health outcomes. Weight gain in adults aged 18 – 35 years had stronger negative associations with critical outcomes such as cancer risk and mortality compared to weight gain at later ages. Developing effective approaches to reduce weight gain in young adults was therefore an important public health priority and focus of the SNAP study.

Participants

SNAP targeted an enrollment of 600 participants (25% men and 25% racial / ethnic minorities), age 18–35, with a BMI of 21–30.9 kg/m2. Eligibility requirements focused on ability to participate in the program (e.g., internet access, English speaking), safety (no history of eating disorders, ability to walk for activity) and completion of screening and baseline assessment visits.

Potential subjects were excluded due to pregnancy, diabetes, alcohol or substance dependence, psychiatric disorders, and any medical problem that could cause unintentional weight change.

A total of 599 subjects were enrolled and randomly assigned into one of three treatment arms. 202 participants were enrolled in the control group, 197 assigned to the large changes group, and 200 assigned to the small changes group.

Design

The Study of Novel Approaches to Weight Gain Prevention (SNAP) was a 3-armed randomized controlled clinical trial that compared self-regulation with small daily behavior changes (Small Changes), self-regulation with large periodic behavior changes (Large Changes), and a minimal treatment control.

The Control group attended one face-to-face meeting where they were introduced to the issue of weight gain, the concept of self-regulation, and an overview of both Small and Large Change approaches to potentially prevent weight gain.

The Small and Large Changes interventions both began with 10 face-to-face group meetings over 4 months. Participants in Small Changes were taught to make daily small changes (approximately 100 kcal/day) in both diet and physical activity. Participants were given pedometers and instructed to add 2000 steps per day above their baseline activity level.

Large Changes focused on losing weight during the initial four-month program to create a buffer against subsequent weight gain. To achieve this, participants were prescribed a calorie goal based on a 500- 1000 kcal deficit from baseline to use during the initial 8 weeks. They were also encouraged to gradually increase moderate intensity physical activity to a goal of 250 minutes/week, the level recommended for weight loss maintenance.

All participants were scheduled to complete assessments at baseline, month 4, year 1 and year 2. To encourage self-regulation, participants were instructed to weigh themselves daily and submit their weight via the study website, text message or email. They received monthly email feedback on their weight, which was based on a color-coded system and either reinforced their success, encouraged problem-solving, or recommended additional strategies to help reverse weight gain. Each year, participants were invited to join two 4-week online refresher campaigns reinforcing the behaviors taught during the initial program. All participants received identical quarterly newsletters and personalized feedback reports on their assessment data, including the Control group.

The primary outcome was the mean weight gain over an average follow-up of 3 years. Secondary outcomes were the proportion of participants gaining ≥1 pound (chosen to represent a stringent criterion of weight gain over baseline) and the incidence of obesity (BMI≥30 kg/m2) over the 3 years.

Conclusions

Self-regulation interventions involving small or large changes were both effective in reducing the mean weight gain relative to control over an average follow-up of 3 years. The Large Changes intervention successfully decreased the proportion of participants who experienced weight gains ≥1 pound over the follow-up, and both interventions reduced the incidence of obesity during follow-up by almost 50% relative to Control, representing a clinically significant reduction in risk of developing obesity.

Wing RR, Tate DF, Espeland MA, et al. Innovative Self-Regulation Strategies to Reduce Weight Gain in Young Adults: The Study of Novel Approaches to Weight Gain Prevention (SNAP) Randomized Clinical Trial. JAMA Intern Med. 2016;176(6):755-762. doi:10.1001/jamainternmed.2016.1236

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