Body mass index and illness in rural Sarawak

This paper reports findings of a cross-sectional anthropometric survey of 447 men and 564 women aged > 18 years of the Iban tribe in rural Sarawak. The percentage of each approximately 10 year cohort with body mass index (BMI: kg/m2) < 18.5 increased progressively with age > 40 years in both sexes. BMI and arm-muscle plus bone cross-sectional area (AMBA) were influenced significantly by reported single symptoms in men and two concurrent symptoms in women. Sensitivity of BMI < 18.5 for identifying those reporting symptoms of illness was 21% in men and 29% in women. Independently of illness effects, values of stature, BMI and AMBA in men, and stature alone in women, were significantly greater in those farming plots with the shortest time left fallow, suggesting their comparative success. The BMI of men may reflect primarily their economic activities, while that of women their experience of illness; the AMBA may also be a better overall index of health than BMI in this population.