Can you afford to exercise? Effects of time and money income on physical activity and the body mass
- Presenter:
Chair: Vilma Carande-Kulis; Discussant: Timothy Classen Wed June 7, 2006 8:00-9:30 Room 226
Rationale: Much has been told about how technological advancements have lowered the price of food and reduced physical demands of work, both of which have been attributed to increased body mass amongst Americans. However, while this explanation of obesity does explain long-term trends in body mass, it should not be forgotten that basically obesity is a micro-level phenomenon. At any point in time individuals take technological advancements as given and then they make behavioral choices which show up in heterogeneity in the weight outcomes. These individual choices are a function of various socio-economic processes which may interact in various ways.
Objectives: The objective of this paper is to analyse the determinants of physical exercise and its impact on body mass.
Methodology: We estimate a system of simultaneous equations where weight is determined by exercise levels besides various socio-economic factors and exercise level is in turn determined by weight and various socio-economic factors. We believe that exercise by its sheer time intensiveness has a large time cost, even when its direct monetary costs may be low, for example in a simple exercise of walking in the park. The time costs therefore add to the opportunity costs of undertaking physical exercise. To the extent that individuals are uniformly endowed with 24 hours in a day, clearly they will allocate their time such as to maximize their utility a crucial component of which is the money or budget constraints. Thus allocation of time to physically demanding activities will determine the body weight of an individual. However, the need to do exercise may itself be motivated by the body weight. We use the NLSY79 data for the years 1998-2002, the only years for which the NLSY explicitly asked questions on physical activity level. To our knowledge there is no other paper which has used this aspect of NLSY till now.
Results: Preliminary analysis suggests that lack of physical exercise can explain part of an increase in body-weight of an individual. Additionally we find that physical exercise, is most lacking in some income groups.
Conclusions: To the extent that individuals do not choose the technology levels in the economy, their choices are revealed through their use of their resources such as to maximize utility. Since overweight does have a disutility clearly individuals who still end up with an uncomfortable level of body weight must be constrained either by money income, or low discount rates, or time. We approached the problem of obesity from time perspective, and our analysis suggests that policy should intervene in the time use of individuals such as to gear them towards some regular basic level of physical exercise.
