Can Adolescents' Obesity Be a Consequence of Peers Lifestyles?

Abstract

Obesity is an important problem of public health, which is often initiated by unhealthy behaviours during adolescence. Food habits among young people are generally influenced by their peers, the so-called "peer pressure", as well as other hazardous consumptions such as alcohol, tobacco and drugs. In this work, obesity is viewed as a household produced good, and self-image and social interactions are likely to play a key role in determining adolescent weight. The main objective of this paper is to identify the risk factors which may explain obesity/overweight among the group of adolescents, according to the Body Mass-for-age, a medical criterion alternative to the BMI adapted to adolescents. Moreover, it aims to draw attention to the dimension of the problem in a risk group composed of potential future obese adults, with all the associated health costs. Particular attention is paid to the potential influence of the peer pressure effect on obesity, since consumption decisions are affected by age peers. A recursive simultaneous equation model, involving two binary choice variables, has been developed, incorporating the importance of peer effects and to control its potential endogenous nature. Control variables include age, gender, school performance, family cohesion, friendship cohesion, social and economical family level, food habits, sports practice, and consumption of addictive substances. The data used are from a Portuguese survey on the health of adolescents made in 2002. The universe of this survey is composed of students in the 6th, 8th and 10th years of secondary education, with ages between 11 and 25 years old. The key finding is that peer effects play a significant role in the probability of obesity. Dieting and corporal self-image are also important determinants of obesity.