Relative leg length as a biological marker to trace the developmental history of individuals and populations: growth delay and increased body fat.

The purpose of this study was to determine whether differences in leg length index are related to differences in body fat. The study included a cross-sectional sample of 21,021 subjects ranging in age from 2 to 90 years who had anthropometric information and poverty income ratio that participated in the third National Health and Nutrition Survey (NHANES III) of the United Stated conducted during 1988-1994. Of the total 21,021 participants, 7,810 were non-Hispanic white (3,900 men and 3,910, women), 8,134 were African-American black (3,127 men and 2,889 women) and 6,237 were Mexican-American (3,221 and 3,016 women). In both males and females and in all three ethnic groups and across socio-economic status (measured by the poverty income ratio) a low leg length index is associated with increased body fat (measured by skinfold thickness) when compared with those with high leg length index. It is postulated that a low leg length index reflects the consequence of negative environmental conditions leading to growth delay. Previous studies indicate that individuals exposed both during development and adulthood to under-nutrition respond through inter-related physiological mechanisms oriented at improving energetic efficiency and low oxidation of fat. These interrelated compensatory physiological adjustments work together to promote fat storage among growth delayed individuals or populations.