A year-long, multi-faceted, school-based obesity intervention program for young children in England’s West Midlands region failed to produce any significant results, researchers reported.
A total of 15 months afterward, mean body mass index-z (BMI-z) scores were not significantly different in children who participated in the program at ages 5-6, compared with a control group that received standard health education (mean difference -0.075; 95% CI -0.183 to 0.033; P=0.175), said Peymané Adab, MD, of the University of Birmingham in England, and colleagues.
Mean BMI-z scores were not significantly different 30 months post-intervention either (mean difference -0.027; 95% CI -0.137 to 0.083; P=0.186), according to the results of the study online in The BMJ.
The study found no significant differences in any of the secondary outcomes, including total daily energy intake (mean difference -273.658; 95% CI -724.284 to 176.967; P=0.118), levels of physical activity (mean difference -0.224; 95% CI -5.344 to 4.896; P=0.910), and systolic blood pressure (mean difference 0.577; 95% CI -1.431 to 2.584; P=0.459), the authors reported.
“Our research, combined with wider evidence, suggests that schools cannot lead on the childhood obesity prevention agenda,” Adab said in a statement.
“Whilst school is an important setting for influencing children’s health behaviour, and delivery of knowledge and skills to support healthy lifestyles is one of their mandatory functions, widespread policy change and broader influences from the family, community, media, and the food industry is also needed,” added another of the co-authors, Miranda Pallan, PhD, also of the University of Birmingham.
The West Midlands Active lifestyle and Healthy Eating in School Children (WAVES) study included approximately 1,200 students ages 5-6 at 54 state-run primary schools. The year-long obesity intervention program had four main components: 30 minutes of moderate to vigorous physical activity each school day, cooking classes for students and parents that emphasized healthy eating, a 6-week program that encouraged healthy eating and physical activity, and dissemination of information on opportunities to be active over the summer.
The trial was designed to address limitations identified in previous research. The sample size was large enough to detect clinically significant differences in adiposity, a comprehensive process evaluation, an assessment of longer-term effects using a range of adiposity and psychosocial measures, and an objective measure of physical activity: the Actiheart monitoring device, Adab and colleagues said.
Asked for her opinion, Sarah Armstrong, MD, of Duke University in Durham, NC, said that despite the negative results, the program may have benefited some children: “It is critical for people to understand that these interventions are not harmful, and lack of ‘effect’ on BMI at this age should never be the deciding factor as to whether this program has overall benefit for children and for future health.”
This was a well-designed trial of lifestyle modifications implemented in the school setting, she said. “The challenge with this setting is that in a given population, only a fraction of children already have developed excess weight, so one would expect the majority of kids, who are healthy weight, to increase their BMI as part of healthy development. The ‘science’ would be more clear if only those children at risk were included, but for practical and ethical reasons, this is not feasible to do in a school setting without stigmatizing those children.”
A similar trial in the United States, the HEALTHY study, which was done in middle-school children, had results similar to the WAVES study, Armstrong noted.
Adab et al said that one reason for the null results may be the difficulties schools had in implementing the program. No school delivered all the program components exactly per protocol, and some schools failed to deliver some or all of the components. This may have attenuated any positive effects. “In addition, due to competing demands on teachers, components that required greater teacher input tended to be less well implemented. This suggests that delivery of a more intensive teacher-led intervention in a school setting would not be feasible without additional resources.”
Another study limitation was that only 60% of children underwent clinical measurements; the remainder did not have parental consent to be measured. This may have introduced a selection bias, the researchers said. “However, a pupil-level comparison of demographic characteristics (gender, ethnicity, deprivation) between those with and without consent did not show any major differences.
“Although wider implementation of this intervention cannot be recommended for obesity prevention, the lower cost components could be considered by schools to fulfill their mandated responsibilities for health and well-being education. Within the context of the wider evidence, it is likely that any effect of school-based educational, motivational, and skill-centered interventions on obesity prevention is small.”
The study was funded by the National Institute for Health Research.
No study authors reported having financial relationships.
Armstrong reported having no financial relationships.