| Abstract: |
Childhood overweight and obesity have increased alarmingly in recent decades
all over the world, particularly in middle-income countries like Brazil,
Mexico and China. In response to the obesity epidemic, several states and
governments have introduced restrictions on sales of high-calorie
low-nutrient-dense foods and beverages in schools. However, most school
canteens around the world continue to offer such unhealthy products. The lack
of clear evidence about the impacts of junk food/beverage availability on
childhood overweight potentially contributes to delaying the application of
regulatory policies. In fact, sales of junk food represent an important source
of revenues for schools, especially in contexts of budgetary pressure. Based
on a representative sample of Brazilian middle school students, this article
takes advantage of local initiatives that began in 2001 aimed at banning sales
of junk food and beverages in schools. Among other effects, instrumental
variables estimates show that in-school soft drink availability increases male
BMI and overweight risk. As expected, the impacts tend to be stronger on
non-poor students. No effect was found for girls, probably because of
voluntary substitutions with healthier foods to control total calorie intakes
and limit weight gain. Alarmingly, in-school junk food/beverage availability
is positively correlated with overall junk food/beverage consumption and
negatively correlated with overall healthy food intakes. In conclusion, this
article provides clear evidence that banning sales of unhealthy products in
schools is a useful tool to fight against the worldwide increase in childhood
overweight, even in middle-income countries. |