Economics of Obesity: Nutrition and Physical Activities Substitution Effect

Introduction: Scientific evidence has demonstrated that child obesity depends on education and economic status of parents, and geographical location. Differently from the majority of published studies, we explain obesity in terms of a rigorous economic model suitable to design a science based health policy scheme. The model is based on a neoclassical approach, and analyzes the obesity problem in terms of a set of nutritional and physical activity choices. Methods: We propose a two-steps methodology of economic choice modelling. In the first step, we suppose a utility model, where people choose the most efficient combination between calories intake, and energy consumption. In the second step, we estimate the cross elasticity between the utility of nutrition and that of physical activity, given the observed levels of Body Mass Index. A case study referred on a population of 898 students (age 11-19) in the South of Italy is presented. Results: The estimation of the cross-elasticity between and across different types of foods and physical activity, allows the comparison between different social groups. Students belonging to lower income groups shows higher preference towards high calories foods, with respect to healthy food. Similarly, students belonging to parents with higher education, show higher preference towards physical activity, in respect to food consumption. Conclusion: The estimation of the cross-elasticity is a valuable information to public policy aimed at the reduction of obesity. Diversified policy measures may be targeted to specific social groups, in order to increase the effectiveness of the policy and to reduce social inequalities.