# Heterogeneous effects on body mass index in the “checkup championship”: A behavioral science-based health promotion program by health interest level

## TL;DR

A health promotion program using behavioral science reduced BMI more in people with low or medium health interest than in those with high interest.

## Contribution

The study shows that behavioral science-based programs have heterogeneous effects depending on health interest levels.

## Key findings

- Participants had greater BMI reduction than non-participants (−0.36 vs. −0.12 kg/m²).
- Significant BMI reduction was observed in low and middle health interest groups.
- No clear BMI reduction was found in the high health interest group.

## Abstract

Behavioral science principles, including approaches such as gamification, commitment strategies, and nudges, are widely used in health promotion programs to prevent non-communicable diseases. These approaches are expected to influence behavior change regardless of health interest; however, their effectiveness remains unclear. This study evaluated the impact of a behavioral science-based health promotion program on body mass index (BMI) reduction across different levels of health interest.

This study evaluated the “Checkup Championship,” a program that applies various behavioral science strategies to improve health checkup results for employees at Hakuhodo DY Group in Japan. Participants in the program in 2020 were compared with non-participants. Health interest was classified as low, middle, or high based on a single-question assessment. A linear regression model analyzed BMI changes between 2019 and 2020, using the inverse probability weighting of propensity scores to adjust for background differences between groups.

A total of 410 participants and 390 non-participants were included in the study. BMI reduction was greater among participants than non-participants (−0.36 kg/m2 vs. −0.12 kg/m2). A significant BMI reduction was observed in the middle (average treatment effect [ATE]: −0.30 kg/m2, 95 % confidence interval [CI]: −0.55, −0.06) and low health interest groups (ATE: −0.34 kg/m2, 95 % CI: −0.61, −0.08); however, no clear BMI reduction was seen in the high health interest group.

The “Checkup Championship” demonstrated effectiveness, particularly among individuals with a lower health interest. Health programs incorporating diverse behavioral science strategies may help reduce health disparities.

•Behavioral science program lowers body mass index in low- and mid-health interest groups.•No clear body mass index reduction observed in the high-health interest group.•The study compares participants and non-participants in a workplace health program.•A linear regression model analyzed body mass index changes from 2019 to 2020.•The Behavioral science-based health programs can reduce health disparities.

Behavioral science program lowers body mass index in low- and mid-health interest groups.

No clear body mass index reduction observed in the high-health interest group.

The study compares participants and non-participants in a workplace health program.

A linear regression model analyzed body mass index changes from 2019 to 2020.

The Behavioral science-based health programs can reduce health disparities.