Energy expenditure among farmers in developing countries: what do we know?

The trend toward overweight and obesity in developing countries is often assumed to be due, in part, to reductions in energy expenditure associated with the transition from agrarian to urban lifestyles. In this article we first review the published studies on energy expenditure in farming populations living in developing countries, populations generally assumed to have high levels of energy expenditure. To facilitate comparison we express energy expenditure as physical activity level (PAL), i.e. the ratio of total daily energy expenditure to basal metabolic rate. Then, with the goal of better understanding variability in energy expenditure between different human groups, we focus on case studies of women farmers in Colombia and Brazil for whom we have good ethnographic data. The published studies reviewed indicate that most farmers have PAL values in the moderate physical activity range, but toward the high end of that range. PAL values of male farmers tend to be higher than female, and show greater seasonal variation. The case studies illustrate that women farmers, living in broadly similar environments, and dependent on the cultivation of the same crop can have quite different patterns of physical activity and hence PAL values. These differences are a function of differences in behavior related to social and cultural variables like the organization of work at the household level and perceptions of how food crops should be processed, as well as micro-level ecological factors.