The impacts of free school lunch policies on adolescent BMI and mental health: Evidence from a natural experiment in South Korea

In spring 2015, the South Korean province of South Gyeongsang stopped providing free school lunches to primary and secondary school students while large portions of schools in other provinces continued to provide free lunches at school. After the provincial government faced strong opposition, South Gyeongsang reintroduced the free-school-lunch program the very next year. Using a difference-in-differences design, we exploit these policy changes to evaluate their impact on students' body mass index (BMI) and on a measure related to students’ mental health status (MH). Our results show that the abolishment of free school lunches harmed (female) underweight students by causing additional weight losses of about 4.5 percent whereas the reintroduction of free school lunches led to an average weight loss of 2.1 percent among overweight students (both male and female). Moreover, the school lunch policy changes had significant impacts on our MH measure: crying without any reason increased when the free-school-lunch policy was abolished and it decreased when the policy was reintroduced. The results are of great interest to decision makers: introducing free school lunches helps to achieve healthier weights and decreases crying without any reason and as a result, benefits student welfare. Free-school-lunch policies, therefore, may provide simple and inexpensive means to improve the health and welfare of students.