PortionControl@HOME: Results of a Randomized Controlled Trial Evaluating the Effect of a Multi-Component Portion Size Intervention on Portion Control Behavior and Body Mass Index

BACKGROUND Food portion sizes influence energy intake. PURPOSE The purpose of this paper is to determine effectiveness of the "PortionControl@HOME" intervention on body mass index and portion control behavior. METHODS A randomized controlled trial among 278 overweight and obese participants was conducted. PortionControl@HOME aimed to increase: portion size awareness, portion control behavior, portion control cooking skills, and to create a home environment favoring portion control. RESULTS Intention-to-treat multi-level regression analysis indicated statistically significant effects of the intervention on portion control behavior at 3, 6, and 12 months follow-up. The effect on body mass index was significant only at 3 months follow-up and when outliers (n = 3) were excluded (B = -0.45; 95%CI = -0.88 to -0.04). The intervention effect on body mass index was mediated by portion control behavior. CONCLUSIONS The intervention improves portion control behavior, which in turn influence body mass index. Once the intervention ceased, sustained effects on body mass index were no longer evident. (Current-Controlled-Trials ISRCTN12363482).