Treating pediatric obesity is challenging. The objective was to evaluate effect of receiving a bicycle on (a) physical activity, (b) sedentary activity, (c) Body Mass Index (BMI), and (d) eating habits.

A stepped-wedge randomized controlled trial of 6- to 12-year-old patients with overweight/obesity was conducted April 2012–2018. Participants were randomized to wait 0, 2, 4, or 6 months for a bicycle. Outcomes on activity, BMI and eating were collected at 3, 6, 9- and 12-months after children received a bicycle.

A total of 525 participants with 387 (74%) completed 3-month follow-up questionnaire, and 346 (66%) completed 12-month follow-up visit. Participants were mostly Latino/a (71%) and low income (58%), and 31% had never ridden a bicycle. Median baseline BMI was 98th percentile. At 3 months, 62% reported bicycle use last week, on average 3.6 days. Time spent on sedentary activities decreased by 48 min/day (p = 0.04), and time spent playing sports increased by 1.7 h/week (p < 0.01). No reduction in BMI was seen. Consumption of sugary drinks decreased (by 0.59 servings/week, p < 0.01), and consumption of vegetables increased (0.71 servings/week, p = 0.04). At 12 months, sedentary time, sugary drink and vegetable consumption remained significantly more favorable than at enrollment (p < 0.01, p < 0.01, p = 0.04 respectively), but not significantly different (p = 0.47 for sedentary, p = 0.73 for sugary drink) and significantly less favorable (p < 0.01 for vegetables) than at the time of intervention.

Participants reported riding bicycle, improved activity and dietary habits, though reversion towards baseline behavior was seen by one year and no change in BMI from enrollment.