Objective  To explore mediation and moderating effect of health concern on the relationship between breakfast habit and sub-health in adolescent and adult community residents.

  Methods  We recruited 3 969 permanent residents aged 14 years and above in urban communities in three provinces across China using stratified multistage random sampling and carried out an anonymous survey among the residents between March and September 2018. A questionnaire on demographics, lifestyle and health consciousness and Sub-Health Measurement Scale Version 1.0 (SHMS V1) for assessment on sub-health were used. General linear model and structural equation model were adopted to analyze mediation and moderating effect of health concern on the relationship between breakfast habit and sub-health.

  Results  Health concern played a significant moderating effect on the relationship between breakfast habit and sub-health (F = 4.412, P < 0.001) and a partial mediation effect on the association of breakfast habit with physical, mental and social sub-health among the residents. The size of direct effect of breakfast habit on physical, mental and social sub-health were 0.295 (95% confidence interval 95% CI: 0.256 – 0.336), 0.189 (95% CI: 0.150 – 0.225) and 0.217 (95% CI: 0.181 – 0.256) and that of indirect effect of breakfast habit on physical, mental and social sub-health through health concern were 0.052 (95% CI: 0.040 – 0.063), 0.063 (95% CI: 0.051 – 0.075) and 0.058 (95% CI: 0.046 – 0.070), respectively.

  Conclusion  Urban community residents with unhealthy breakfast habit and low health concern are more likely to have physical, mental and social sub-health symptoms and health concern influences the impact of breakfast habit on sub-health among the residents.