Short summary

The GHK intervention was developed according to the United Kingdom Medical Research Council's framework for developing and evaluating complex interventions. A pilot- and feasibility study was conducted during December 2022-April 2023, and the intervention was subsequently adapted and adjusted. The GHK main trial is a two-school-year cluster-randomized school- and community trial designed to investigate the effect of the multi-setting, multi-component GHK intervention program on weight developme

Rationale

Overweight and obesity among children is a global problem affecting more than 41 million children under the age of 5 years. The World Health Organization (WHO) describes childhood obesity as one of the most serious public health challenges worldwide for the 21st century​. The prevalence of overweight and obesity in Danish children is 12-13% in primary school and increases to 18-19% at the time of graduation​, why early prevention is important. In the adult population 51% are estimated to be overweight or obese.

Overweight and obesity have many negative health consequences for children during their early years and in later life. For instance, children who have overweight or obesity are more likely to experience bullying, stigmatization and suffer from low self-esteem, anxiety, and lower quality of life​. In addition, children with overweight and obesity have an increased risk of overweight and obesity as adults, which is well known to lead to poorer health and well-being and marked economic negative effects for the individual and for society.

There are stark inequalities in the prevalence of childhood overweight, both worldwide and in Denmark, contributing to the health inequality found in most countries. In Denmark, the overweight prevalence among children aged 6-7 years in high-income families is 11% compared to 26% in low-income families. Among children aged 14-15 years, the prevalence of overweight is almost 30% in families with short education compared to 10% among those from families with long education.

Many trials have been conducted to reduce childhood overweight and obesity, and several comprehensive systematic reviews have investigated the effect of different interventions in preventing childhood overweight and obesity. However, most of the earlier studies find no or only small effects on children's body mass index (BMI), and the evidence of long-term effects is limited.

Thus, there is a strong need to develop new innovative approaches and programs that effectively can prevent overweight among all children, starting early in life and embedding promising programs and integrated approaches into everyday practices.

Generation Healthy Kids is a cluster-randomized school and community trial in which 24 local schools will be randomly allocated to intervention or control. The overall study objective is to investigate if a 2-school-year multi-setting, multi-component intervention focusing on healthy diets, physical activity, sleep and screen media habits in the school and local community can promote healthy weight and body composition in children who are in 1st and 2nd grade at inclusion (i.e., age 6-9 years at inclusion). We will also investigate the intervention's effects on dietary intake and nutritional status; food competences; physical literacy, activity levels, and fitness; sleep and screen media habits; growth; cardio metabolic health; cognitive and motor functions; school performance; and mental health and wellbeing. Furthermore, we will evaluate the implementation of the intervention.

In continuation of the above, we will investigate if the intervention can reduce social inequality in the outcomes, as well as explore potential effect modifiers such as sex, ethnicity, genetics, epigenetics etc. We will also explore associations between sociodemographic characteristics, health behaviours and outcomes cross-sectionally and longitudinally and use these data to validate and compare relevant measurement tools.

The primary outcome is fat mass (FM) in kg. We hypothesize that the combined intervention components will counter the development of increasing overweight and unhealthy weight with age and thus will cause less FM gain in the intervention group compared with the control group.

Description of the cohort

Children in first and second grade on 24 Danish schools will be invited to participate in the study approximately 2000 children.

Data and biological material

Questionnaire data (background information, well-being, screen media use, food intake, sleep), physical examinations (fat mass, fitness, blood pressure, cognitive tests, well-being).

Collaborating researchers and departments

Nutrition, Exercise, and Sports, University of Copenhagen

• Nikolai Baastrup Nordsborg

Center for Klinisk Forskning og Forebyggelse, Region Hovedstaden

• Ulla Toft

Sports Science and Clinical Biomechanics, University of Southern Denmark

• Jens Troelsen