5.2. Reduction in energy expenditure

A decrease in BMR in the absence of reduced growth rate or an improvement in mechanical efficiency has not been demonstrated in undernourished children to explain the reduction in total energy expenditure shown in the studies discussed above. Even if these phenomena had occured without being detected, they could not be the sole explanation for the reduction in energy expenditure. Infants, preschool children and school-age children did become less active and engaged less or no longer in certain activities (CHAVEZ et al., 1972; CHAVEZ and MARTINEZ, 1979; RUTISHAUSER and WHITEHEAD, 1972; VITERI and TORUN, 1981; TORUN and CHEW, unpublished; SPURR and REINA, 1989a).

This was more evident in younger children, probably because they were subject to less social constraints and peer pressure. In the case of children who go to school, it seems that the school routine, which occupies a large proportion of daytime and restricts free physical activity, tends to mask the potential differences in activity related to nutritional status. The differences may become evident when children are given the opportunity and are encouraged to be more physically active, as seen in the summer-camp studies of SPURR and REINA (1988c).