Sitting around the elf campfire sharing toasted marshmallows (in moderation) provides a socially beneficial environment for discussing “one of the most serious public health challenges of the 21st century” (WHO, 2019a). Being overweight or obese is described as “abnormal or excessive fat accumulation that presents a risk to health” (WHO, 2019b). In 2016, 124 million children and adolescents aged 5-19 were obese, equating to 6% of girls and 8% in boys across the globe (The Lancet, 2017).
Children who are overweight and obese in childhood are likely to be obese in adulthood and more likely to develop largely preventable noncommunicable diseases (NCD) such as cardiovascular disease and diabetes at a younger age (WHO, 2019a). Obese children also rate their personal wellbeing as low, leading to mental health risks associated with body dissatisfaction and low self-esteem (Office for National Statistics, 2014).
Recent rates of obesity in children and young people in northwestern Europe have ‘flattened’ (The Lancet 2017). Obesity rates in England in 2017-2018 for children aged 4-5 years were 9.5%, rising to 20.1% in children aged 10-11 years (Public Health England, 2019). Any variance in weight is detrimental to health and in the case of excessive weight, weight loss and maintenance of weight loss is hard to achieve (The Lancet, 2017). The key point to note here is that obesity is preventable (Agha and Agha, 2017) and the prevention of childhood obesity is a high priority (WHO, 2019a).
In 2018, Adab et al reported on a 12 month intervention called the West Midlands ActiVe lifestyle and healthy Eating in School children (WAVES) study, which was designed to “assess the effectiveness of a school and family based healthy lifestyle programme compared with usual practice” through a cluster randomised controlled trial, aimed at preventing excess weight in primary school children.
The intervention randomly selected 200 schools within 35 miles of the research centre. Of the 144 schools that met the eligibility criteria, final recruitment in 2011/2012 involved 54 schools with a population of 1,467 year 1 pupils aged 5-6 years. At this point, baseline measurements were undertaken on 1,392 pupils and then schools were randomly assigned to one of two arms of the study. 53 schools remained in the study: 25 schools received the intervention in the following year, while 28 schools became the control arm. There were two recruitment periods, group 1 in 2011 and group 2 in 2012.
The WAVES complex intervention ran over 12 months and had two aims:
Aim 1: Increase children’s physical activity levels (three components)
- Provision of opportunities for 30 additional minutes of physical activity in school time each day (teacher led)
- Six week skills based interactive programme in conjunction with Aston Villa Football Club (called Villa Vitality)
- Mail out to local families of physical activity opportunities outside of school every six months.
Aim 2: Improve children’s dietary intake (two components)
- School-led family workshops to increase knowledge, healthy preparation and cooking skills
- Villa Vitality programme provided two sessions over six weeks with integrated family ‘challenges’ and a class based project.
The primary outcome measure was the difference in mean BMI (defined as a person’s weight in kilograms divided by his/her height in metres squared) between the intervention arm and the control arm. The first follow up was 3 months post intervention, and the second follow up was 18 months post baseline.
There were no statistically significant differences between the intervention or control arms at either the first or second follow up point.
The secondary outcome measures linked to anthropometric (scientific study of measurements and proportions of the human body – weight, height, body fat, waist circumference and skinfold thickness) dietary, physical activity and psychological measurements (including assessment of harm) also showed no statistically significant difference between intervention arms.
Despite a six year development process beginning in 2005, the WAVES study intervention had no statistically significant effect on BMI scores or the prevention of obesity. The authors concluded that:
schools are unlikely to impact on the childhood obesity epidemic by incorporating such interventions without wider support across multiple sectors and environments.
Strengths and limitations
The article (which is open access if you want to read it in full) presents a detailed reflection on a complex obesity prevention intervention for 6 and 7 year olds. Written for the BMJ, which is a weekly, peer reviewed medical research journal, the technical research language and vast array of statistical information is daunting.
An extended abstract provides a good overview of the WAVES study and is relatively easy to interpret. However, to fully appreciate the scope and scale of the intervention, engagement with the detailed statistical analysis and tabulated methodology is required.
The authors discuss a range of factors as to why there was no meaningful statistical differences after completion of the intervention but one key factor appears to be that “no school delivered all components completely as intended”, particularly in relation to providing the 30 additional minutes of physical activity per day, with only 17% of schools achieving high implementation of this teacher led initiative. Described as low implementation fidelity, this raises the issue of trying to ‘squeeze’ additional interventions into primary curriculum delivery.
Although this article was published in 2018, the development of the WAVES intervention began in 2005 and since its implementation in 2011-2012, there have been substantial changes linked to the promotion of physical activity and healthy eating. This includes updated guidance on Childhood obesity: a plan for action in 2017 by the government, meaning this article may not reflect current thinking for tackling childhood obesity in primary schools.
Implications for practice
Schools have mandated responsibilities linked to the provision of education on health and wellbeing. Although the WAVES intervention was carefully planned and trialled, the lack of statistically significant changes mean the authors do not recommend the wider implementation of the intervention, suggesting “it is likely that any effect of school based educational, motivational, and skill centred interventions on obesity prevention is small”. Instead, the authors advocate a wider systems approach should be considered, which involves multiple agencies and policy changes that support the promotion of, and opportunities to, support healthy behaviours.
The doubling of incidence of obesity between 4-5 years and 10-11 years demonstrates that something is happening between the time children start and leave primary school in England. Can the physically active, playful environment associated with pre-school settings, where healthy habits for life are introduced and nurtured, be replicated in schools, particularly at a time when opportunities for play, physical and recreational activities are being diminished?
Conflicts of interest
None associated with this blog.
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Adab P, Pallan M, Lancashire E. et al (2018) Effectiveness of childhood obesity prevention programme delivered through schools, targeting 6 and 7 year olds: cluster randomised controlled trial (WAVES study) BMJ 2018 360:k211
Agha, M. and Agha R. (2017) The rising prevalence of obesity: part A: impact on public health International Journal of Surgery. Oncology 2017 2 (7) e17.
The Lancet (2017) Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016: a pooled analysis of 2416 population-based measurement studies in 128·9 million children, adolescents, and adults. The Lancet 2017 390 (10113) 2627-2642.
Childhood obesity: a plan for action. GOV.UK website, last accessed 20 Aug 2019.
Childhood overweight and obesity. World Health Organization website, last accessed 15 Aug 2019a.
Measuring National Well-being – Exploring the Well-being of Children in the UK: 2014. Office for National Statistics website, last accessed 17 Aug 2019.
NCMP and Child Obesity Profile. Public Health England website, last accessed 17 Aug 2019.
What is overweight and obesity? World Health Organization website, last accessed 17 Aug 2019b.