Longitudinal changes in preschoolers’ adiposity indicators according to compliance with 24-hour movement behavior guidelines: results from the ToyBox-study

There is a lack of studies evaluating longitudinal changes in adiposity indicators and the association with 24-hour movement behavior guidelines in preschoolers. Therefore, this study aimed to investigate associations between changes in Body Mass Index (BMI) z-scores, waist circumference and waist-to-height ratio, and compliance with the 24-hour movement behavior guidelines in three- to six-year-old children from a European sample.

In total, data from a European sample of 719 preschoolers (50.9% boys, 4.76 ± 0.45 years) were analyzed at baseline and one year later. Physical activity (steps/day) was objectively measured using Omron pedometers. Screen time and sleep duration were subjectively measured using a parental questionnaire. Height, weight and waist circumference were measured by well-trained researchers, using standardized procedures and equipment, and were used to calculate BMI z-score and waist-to-height ratio. Linear mixed-effects models were used to investigate associations between changes in adiposity indicators (BMI z-score, waist circumference and waist-to-height ratio) and compliance with 24-hour movement behavior guidelines.

BMI z-scores changed differently from baseline to follow-up according to compliance with the integrated guidelines, both for weekdays (effect estimate = -0.15, p = 0.001) and weekend days (effect estimate = -0.12, p = 0.046). Preschoolers who did not comply with the integrated guidelines showed a small, significant increase in BMI z-scores compared to compliers having no significant change in BMI z-score. No significant difference between both groups over time was found for waist circumference and waist-to-height ratio neither for weekdays nor weekend days.

The change in BMI z-scores after one year is less optimal for preschoolers who do not comply with the 24-hour movement behavior guidelines compared to preschoolers who comply with the integrated guidelines, although not clinically relevant. Future studies should incorporate longer follow-up periods to observe the effects of compliance to the integrated guidelines on adiposity indicators in preschool children.