Background: Ethnic differences in the association between body mass index (BMI) and body fat suggest that body composition varies across ethnic groups. Objective: To investigate the association between impedance index -a measure of tissue resistivity -and BMI in adults of different ethnic groups (Asian Indians, West Africans and White Caucasians) living in their native countries. Methods: Male (n ¼ 329) and female (n ¼ 277) adult subjects (18-50 years) living in urban areas in the UK, The Gambia and Pakistan were studied. Body weight and height were measured and BMI calculated. The same leg-to-leg bioimpedance instrument was used in each study and impedance index (height 2 (cm)/impedance (O)) used as measure of tissue resistivity. Results: In women, Asian Indians and West Africans had a significantly greater increase in impedance index per unit increase in BMI compared with white Caucasians (Po0.001). In men, Asian Indians had a significantly lower impedance index compared with West Africans and white Caucasians (Po0.001). Conclusion: Different ethnic groups may have different tissue resistivity for the same BMI indicative of systematic differences in body composition.

The weights of 220 infants of Bangladeshi origin attending two clinics in the London Borough of Tower Hamlets were analysed at birth, 6 months and 18 months of age. The weights were compared first with the Tanner-Whitehouse standards derived from English children and then with Indian data from the infants of well-to-do families. The mean weights of the infants of Bangladeshi origin were below the British Tanner-Whitehouse 50th centiles, approximating to the 25th centile values. As the means were similar to those reported from well-nourished Indian infants, it is unlikely that the Bangladeshi infants were undernourished. The reported weights of well-nourished Indian infants appeared to be a more appropriate reference for the infants of Bangladeshi origin than the Tanner-Whitehouse values. However the Tanner-Whitehouse charts can be used, but with their 25th, 10th and 3rd centile lines being taken to read 50th, 25th and 10th centiles, respectively. Significantly more boy than girl infants were brought to one of the clinics.