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Resumo

The energy demands of pregnancy and lactation together with the accumulation of stored fat in human females during development suggest that a critical level of fat may be required for menarche; but multivariate analyses have supported the alternative view that skeletal growth is the main factor. However, significant differences between upper‐ and lower‐body (gluteofemoral) fat suggest that fat distribution may be more relevant than total fat. Using cross‐sectional data from the third National Health and Nutrition Examination Survey (NHANES III) for females aged 10–14, we show that menarche is more closely related to fat distribution than to skeletal maturity. Unit increases in hip circumference are associated with 24% higher odds of menarche while increases in waist circumference and triceps skinfold lower the odds by 7 and 9%, respectively. Those with menarche despite low levels of total body fat have relatively more fat stored in gluteofemoral depots than those without menarche or those with menarche and greater total amounts of fat. In young women with completed growth, age at menarche is negatively related to hip and thigh circumference and positively related to waist circumference, stature, and biiliac breadth; and blood leptin levels are much more strongly related to gluteofemoral than upper‐body fat, suggesting that leptin may convey information about fat distribution to the hypothalamus during puberty. Fat distribution may be relevant because gluteofemoral fat may provide neurodevelopmentally important fatty acid reserves. Am J Phys Anthropol, 2007. © 2007 Wiley‐Liss, Inc.

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