Staying in school for lunch instead of eating in fast-food restaurants: results of a quasi-experimental study among high-school students

OBJECTIVE: Following the adoption of food policies replacing unhealthy products by healthy foods in school, the present study tested the effectiveness of an intervention aimed at encouraging high-school students to stay in school for lunch instead of eating in fast-food restaurants.

DESIGN: A 12-week multi-strategy intervention targeting specific determinants of behaviour was evaluated via a quasi-experimental pre- and post-intervention design. A self-administered questionnaire was employed based on the theory of planned behaviour.

SETTING: An experimental (n 129) and a control school (n 112) in central Canada.

SUBJECTS: High-school students aged 12 to 17 years.

RESULTS: Compared with control school students, those in the experimental school significantly increased the mean number of days that they stayed in school for lunch (relative risk = 1·55; 95 % CI 1·06, 2·27; P = 0·024), as well as the proportion who remained in school for lunch every day (relative risk = 1·21; 95 % CI 1·04, 1·40; P = 0·014). Among the psychosocial variables targeted, only self-efficacy appeared to be influenced by the intervention, mainly because of a decline in control group values. Mediation analysis indicated a significant mediating effect of self-efficacy on the mean number of days that students stayed in school for lunch (bias-corrected and accelerated point estimate = 0·079; 95 % CI 0·0059, 0·1958).

CONCLUSIONS: These results suggest that interventions aimed at enhancing self-efficacy can successfully contribute to students staying in school during lunch time. Such interventions should be considered in obesity prevention programmes adapted to high-school students.