One million skinfolds: secular trends in the fatness of young people 1951-2004

Background/Objectives: There are abundant data on secular trends in the body mass index (BMI) of children. However, BMI is an imperfect index of fatness, whereas skinfold thicknesses provide a more direct measure. This study aims to meta-analyse historical studies of triceps and subscapular skinfold thicknesses in young people aged 0-18 years in developed countries. Subjects/Methods: A total of 154 studies conducted between 1951 and 2003 were analysed, covering 2390 reports at the age x sex x country level, and more than 458 547 young people from 30 developed countries. Percentage body fat (%BF) was estimated using the Slaughter equations. The distribution of fat on the body was indexed by the triceps/subscapular (T/S) ratio. The skewness of skinfold distributions was operationalized by the coefficient of variation and the mean-median difference. Results: There have been increases in triceps and subscapular skinfold thicknesses, at the rate of 0.4-0.5 mm per decade over the period 1951-2003. %BF has been increasing at the rate of 0.9% BF per decade. The distribution of fat on the body, as indexed by the triceps/subscapular (T/S) ratio, has become more central. There has been an increasing positive skew in the distribution of subcutaneous fat thickness in the population. Conclusions: These trends describe very unfavourable changes in the body composition of young people, foreshadowing a potential increase in the incidence of cardiovascular and metabolic disease. European Journal of Clinical Nutrition (2009) 63, 934-946; doi: 10.1038/ejcn.2009.7; published online 18 February 2009