Body mass index and fat patterning of adults in rural Sarawak.

Body fatness distribution is a useful epidemiological and clinical marker of health risk among European and other populations. Prevalence of obesity among adults is rising in many parts of Malaysia, and it is important to understand the extent to which fat patterning is robust across different age groups and between the sexes. This analysis examines fatness and fat distribution in rural Sarawakian adults aged 20 to 80 years to determine the extent to which fat patterning varies by sex and age. Principal component analysis of five skinfolds (biceps, triceps, subscapular, suprailiac and medial calf) shows upper body-lower body fat distribution as contributing most to within-group variation in the sum of five skinfolds for both males and females. When divided into younger and older age groups, clear differences were identified. For the males, while absolute fatness does not change with age, there is a change in fat patterning, with a trunk-extremity component disappearing, and a trunk-lower body pattern persisting. Females experience a decline in subcutaneous fatness across age groups, and while the most important component of fat distribution, trunk to lower body subcutaneous fatness, the same for younger and older women, the second component is different, with upper limb-lower body distribution in the younger age group being replaced with upper to lower trunk distribution. The similarities in fat patterning among males and females suggest that the use of fat patterning indices in this Malaysian population need not be sex-specific, but age group- and sex-dependent differences in the second principal component indicate that they should be used with caution, since the relationships between fat patterning and mortality are still poorly understood among Malaysian populations.