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

Background: Reduced energy expenditure and excessive energy intake have bee n 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 expenditu re and body composition. Design: We measured total energy expenditure (TEE) and resting metabolic ra te (RMR) in 80 young women [40 New Zealand (NZ) Polynesian and 40 NZ Europe an] aged 18-27 y by the doubly labeled water method and indirect calorimetr y, 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 European s (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 ((x) over bar +/- 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 counterp arts (3.8 +/- 1.9 MJ/d, P = 0.005). Similar trends were seen when AEE adjus ted for body weight and TEE/RMR were compared among the subgroups. Body wei ght and RMR together accounted for 66% of the Variation in TEE for the Euro pean 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.