Effects of macronutrient composition of the diet on body fat in indigenous people at high risk of type 2 diabetes.

AIMS: We compared, in New Zealand Maori at risk of type 2 diabetes, advice emphasizing fiber rich carbohydrate and fat reduction (HCHF) and a high protein (HP) diet incorporating food preferences of indigenous people, with a control group (CONT). METHODS: Eighty-four participants were randomized to three groups. Consecutive 8 week periods of supervised weight loss, supervised weight maintenance and unsupervised adherence to the prescribed diet using culturally sensitive methods were employed in intervention groups. Dietary compliance, body composition, blood pressure and metabolic variables were measured. RESULTS: Body weight was reduced throughout on HP -2.6 (95% confidence interval: -4.4, -0.8)kg and HCHF (-1.6 (-3.0, -0.3)kg) compared with CONT. Total body fat (-1.6 (-3.0, -0.3)kg) and waist circumference (-3.0 (-5.7, -0.2)cm) showed sustained decreases on HP compared with CONT. Diet records suggested reasonable compliance with dietary advice on HP. Carbohydrate intake, but not dietary fiber, increased at the expense of fat on HCHF. CONCLUSIONS: While moderate weight loss occurred on both HP and HCHF, HP was associated with some further favorable differences compared with the control group.

Body mass index and waist circumference cutoffs to define obesity in indigenous New Zealanders.

BACKGROUND: The suggestion that body mass index (BMI) cutoffs to define obesity should differ in persons of Polynesian descent compared with Europeans is based principally on the observation that persons of Polynesian descent have a relatively higher proportion of lean body mass for a given BMI. OBJECTIVES: The objectives were to determine whether the relation between BMI, waist circumference, and metabolic comorbidity differs in the 2 major ethnic groups in New Zealand and to ascertain whether ethnicity-specific BMI and waist circumference cutoffs for obesity are justified for Maori (indigenous New Zealanders). DESIGN: Subjects included a convenience sample of 1539 men and women aged 17-82 y (47% Maori, 53% white) with measures of BMI, waist circumference, blood pressure, fasting insulin, glucose, and lipids. The sensitivity and specificity of BMI (in kg/m(2); 30 and 32), waist circumference (80 and 88 cm in women, 94 and 102 cm in men), and waist-to-height ratio (WHtR; > or =0.6) in relation to insulin sensitivity, insulin resistance, and the metabolic syndrome were determined. Receiver operating characteristic curves and areas under the curve (AUCs) were also calculated. RESULTS: No ethnic or sex differences between AUCs were observed for BMI, waist circumference, or WHtR, which showed that these anthropometric measures perform similarly in Maori and European men and women and correctly discriminate between those with and without insulin resistance or the metabolic syndrome 79-87% of the time. Any increase in specificity from a higher BMI cutoff of 32 in Maori was offset by appreciable reductions in sensitivity. CONCLUSION: These findings argue against having different BMI or waist circumference cutoffs for people of Polynesian descent.