Summary Background Measures during the COVID‐19 pandemic, including the closure of schools and sports facilities, may have lasting impact on the physical activity (PA) of children that persists for a long time. Objective To investigate the effect of COVID‐19 measures on screen time and PA in Dutch children pre‐, during‐ and post‐school closures. Methods In cohort A (n = 102, 10.5 ± 3.6 years, 42.4% boys), data on PA and screen time during the lockdown were collected using a questionnaire. In cohort B (n = 131, 10.2 ± 0.9 years, 43.5% boys), data on PA and screen time were collected using a questionnaire and accelerometry 1 year before and after school closure. Results In cohort A, 62% reported less total PA. Self‐reported screen time on week days increased 34 ± 105 min/d during the lockdown. In cohort B, sedentary time as measured by accelerometry, increased by 45 ± 67 min/d and only 20% reached PA levels of 60 min/d compared to 64% in May 2019. Self‐reported screen time increased by 59 ± 112 min/d and 62 ± 130 min/d during week and weekend days, respectively. Conclusions Children were less physically active, and screen time was higher during and after the school closures due to the COVID‐19 lockdown. This is alarming as an active lifestyle in children is crucial in preventing chronic diseases such as obesity.

Background: Early research showed weight gain in children during the COVID-19 pandemic. Objective: To compare changes in BMI z-score of children with overweight and obesity in a personalised lifestyle intervention before and during the pandemic. Methods: Changes in BMI z-score half a year (T6) and twelve months (T12) after the first lockdown were included for 71 children in the ‘2020 during COVID’ group and compared to 48 children in the ‘2019 before COVID’ group, using a marginal model for repeated measures (model 1). Model 2 corrected for lifestyle intervention characteristics, and model 3 corrected additionally for family characteristics. Results: The mean difference in BMI z-score change was significantly different at T12 (+0.07 in 2020 versus −0.09 in 2019, p = 0.022). Model 3 showed significant differences in BMI z-score change at both T6 (+0.15, p = 0.024) and T12 (+0.18, p = 0.016). This model also defined ‘having a mother with obesity’ (+0.13, p = 0.019) and the frequency of no-show consultations (+0.41 per missed consultation per month, p = 0.025) as related factors. Conclusions: Lifestyle intervention in children with overweight and obesity is less successful in decreasing BMI z-score during the COVID-pandemic. Identified risk factors for less success could contribute to identifying children with higher risks for, and possibly prevent, BMI z-score increase.

Lifestyle interventions are the common treatment for children and adolescents with severe obesity. The efficacy of these interventions across age groups remain unknown. Therefore, this study aimed to compare the effectiveness of a lifestyle intervention on health parameters between children and adolescents with severe obesity. A longitudinal design was carried out at the Centre for Overweight Adolescent and Children’s Healthcare (COACH) between December 2010 and June 2020. Children (2–11 years old, n = 83) and adolescents (12–18 years old, n = 77) with severe obesity received a long-term, tailored, multidisciplinary lifestyle intervention. After 1 year, 24 children (28.9%) and 33 adolescents (42.9%) dropped out of the intervention. The primary outcome was the change in body mass index (BMI) z-score after one and two years of intervention. The decrease in BMI z-score over time was significantly higher in children compared to adolescents, the mean decrease was 0.15 (0.08–0.23) versus 0.03 (−0.05–0.11) after one year and 0.25 (0.15–0.35) versus 0.06 (−0.06–0.17) after two years of intervention; p values for the difference between children and adolescents were 0.035 and 0.012. After two years, multiple improvements in cardio metabolic health parameters were observed, especially in children. In conclusion, during our tailored lifestyle intervention, a positive and maintained effect on health parameters was observed in children with severe obesity. Compared to children, the effect on health parameters was less pronounced in adolescents.

Introduction: School closures due to the COVID-19 pandemic affect children’s daily structure, mealtimes, physical activity and sleeping habits, possibly exacerbating weight gain, particularly in vulnerable children with overweight and obesity. This study aims to evaluate both perceived and objectively measured weight gain in children in the Netherlands during the COVID-19 pandemic and the effect of prior lifestyle intervention. Methods: 150 children of the Children, Obesity and Lifestyle during COVID-19 (COLC) study (cohort A) reported perceptions of weight change during the COVID-19 pandemic. Anthropometric data of 65 children with overweight and obesity was collected at the expertise Centre for Overweight Adolescent and Children’s Healthcare in the same period (COACH; cohort B). Results: In cohort A, 43% of children with overweight and obesity perceived weight gain during the pandemic, compared to 15% of lean children. In cohort B, BMI z-score increased significantly (+0.065 SD) within five months. Participation in a lifestyle intervention for >1 year and having parents with Dutch background was associated with less weight gain, specifically in children with obesity. Discussion/Conclusion: In particular children with overweight and obesity seem to be at risk for accelerated weight gain during the COVID-19 pandemic. Prior long-term participation in a lifestyle intervention protects against this weight gain, which emphasizes the importance of strong support for vulnerable populations during health crises and pleads for wide implementation of lifestyle interventions for children.