Adiposity and body fat distribution based on skinfold thicknesses and body circumferences in Czech preschool children, secular changes.

Background: The long-standing widespread prevalence of obesity includes issues of its evaluation. Nutritional status may be assessed using various tools and methods; among others simple anthropometric measurements are well established. Widely used body mass index (BMI), presents an obstacle of needing to calculate a standard deviation score (SD) for correct use in the child population. As BMI overlooks body composition, it is necessary to evaluate fat and muscle mass with different methods. Established skinfolds and circumferences are used in many variations and equations to accomplish that goal; however, the parameters used in these methods also undergo secular changes. Furthermore, secular changes have been documented in fat mass distribution. The aim of the study is to assess secular changes of skinfolds thickness and body circumferences and evaluate their validity for use in clinical practice and population research.

Methods and sample: Our database consisted of a recent (2016-2022) sample with 594 participants (298 males) and a reference sample (from 1990) with 2,910 participants (1,207 males). Both cohorts comprised Czech preschool children, aged 4.00 to 6.99 years. With standard methodology, anthropometric parameters were obtained for 13 skinfolds and eight circumferences, by trained staff. The equations of Slaughter, Durnin and Deurenberg were correspondingly calculated. Statistical evaluation was conducted in the R programming language, using Welch's test, Cohen's d and the Bland-Altman method.

Results: Our study found significant increases in skinfold thickness on the abdomen, chest I. and forearm, with high clinical relevance (p ≥ 0.01; d = range from 0.20 to 0.70). Contrastingly, apart from the abdominal area, a decrease of circumferences was observed. The body fat percentage estimation equations were tested for bias in the recent sample in the context of bioimpedance analysis with the Bland-Altman method. All equations are suitable for application in clinical use.

Discussion: Documented secular changes in fat mass distribution are only part of a contemporary accelerating trend of obesity prevalence. Our findings support the trend of a decline of circumferences and rise of skinfold thickness in corresponding areas, especially on the limbs, that is evidenced by the trend of latent obesity. The results of the study show the need to complement established diagnostic procedures in childhood obesitology with abdominal and midthigh circumferences and optionally even the maximal circumference of the forearm. These circumferences should always be measured alongside the skinfold thickness of the region. Only in this way can the overall adiposity of an individual with regard to secular changes, including the detection of latent obesity, be objectively evaluated.