Energy expenditure of young polynesian and European women in New Zealand and relations to body composition

Abstract

Background: Reduced energy expenditure and excessive energy intake have been hypothesized to cause obesity. New Zealanders of Polynesian origin have a higher prevalence of obesity than do those of European origin. Objective: We investigated relations between components of energy expenditure and body composition. Design: We measured total energy expenditure (TEE) and resting metabolic rate (RMR) in 80 young women [40 New Zealand (NZ) Polynesian and 40 NZ European] aged 18-27 y by the doubly labeled water method and indirect calorimetry, respectively. Each group was partitioned into nonobese and obese on the basis of percentage body fat. Results: TEE and body weight were highly correlated in nonobese NZ Europeans (n = 23, r = 0.76, P < 0.001), obese NZ Europeans (r = 0.58, P = 0.016), and nonobese NZ Polynesians (n = 25, r = 0.59, P = 0.002) but not in obese NZ Polynesians (r = 0.11, P = 0.70). Activity energy expenditure (AEE = TEE RMR) was similar in obese Polynesians and Europeans (x̄ ± SD: 5.5 ± 2.2 and 5.2 ± 1.9 MJ/d, respectively), but significantly higher in nonobese Polynesians (5.7 ± 2.5 MJ/d) than in their European counterparts (3.8 ± 1.9 MJ/d, P = 0.005). Similar trends were seen when AEE adjusted for body weight and TEE/RMR were compared among the subgroups. Body weight and RMR together accounted for 66% of the variation in TEE for the European group but only 17% for the Polynesian group. Conclusion: Care should be taken in applying 'Caucasian norms' relating to energy expenditure to NZ Polynesian people.