Ensuring healthy school dinners and lessons for children and parents about nutrition reduces obesity, a five-year study found.
Policies including swapping fizzy drinks for water, sending children home with nutritional newsletters and not rewarding them with treats led to good eating habits.
In schools which used a nutritional programme pupils were less likely to see increases in body mass index (BMI).
With obesity a rising health threat in Western countries, the researchers said such interventions could lower young people’s weights and avoid disease later in life.
As many as one in two US teenagers and one in three UK teenagers are overweight or obese.
Ensuring healthy school dinners and lessons for children and parents reduces obesity, a five-year study in New Haven, Connecticut found
The study enrolled 600 pupils across 12 schools in New Haven, Connecticut, with children an average age of 11 years old at the beginning.
The schools were divided into four groups of interventions: nutrition only, physical activity only, nutrition and physical activity (dual), or delayed.
In delayed interventions no health-focused messages related to obesity prevention were used.
Each school had a wellness team to watch over the interventions which were measured for their effectiveness.
In schools with more detailed nutrition policies and programmes, students had healthier BMIs – a measure of someone’s weight relative to their height – over time.
They had a BMI increase of less than one per cent, whereas students in schools without the programmes showed increases of three to four per cent.
‘By the end of the study they reported healthier behaviours than their peers in schools without the nutrition policies and programmes,’ the authors, at Yale School of Public Health, said.
‘At the end of the study, these students reported lower consumption of unhealthy foods and sugar-sweetened beverages, although there was no effect on consumption of healthy foods and beverages.
‘The magnitude of effects of the nutrition intervention was stronger over time.’
The interventions tried included encouraging healthy food choices in cafeterias, providing alternatives to unhealthy food during celebrations, and taste-testing new foods.
Physical activity interventions included promoting walking or cycling to school, integrating physical activity into classroom lessons and fitness challenges.
Exercise policies alone had little or no impact on BMI, the research, published in the American Journal of Preventive Medicine, found.
Lead author Professor Jeannette Ickovics said: ‘These findings can guide future school and community interventions.
‘Childhood obesity is a serious health threat, and schools are a vital way to reach children and their families to reduce risks and promote health.
‘These findings strongly support previous administration policies that provided healthier food for all children in public schools.’
The authors suggest ‘prevention may be better than cure’ when it comes to obesity.
And other studies show teenagers of a healthy weight are more likely than other students to remain healthy into adulthood.
‘Students who are already overweight or obese likely need more tailored, intensive interventions,’ the authors said.
Being overweight or obese early in life affects health across someone’s life, they said.
It contributes to a range of chronic diseases such as high blood pressure, diabetes, and depression which can cut lives short.
The study is one of the first school-based intervention studies to follow students through middle school – an age at which healthy habits are formed and can be sustained, the authors said.
Senior study author Professor Dr Marlene Schwartz added: ‘This is some of the strongest evidence we have to date that nutrition education and promoting healthy eating behaviours in the classroom and cafeteria can have a meaningful impact on children’s health.
‘These findings can inform how we approach federal wellness policy requirements and implementation in schools to help mitigate childhood obesity.’
The UK Government’s childhood obesity strategy, revealed in June this year, asked stores to not display unhealthy food at checkouts or buy-one-get-one-free deals.
It will also consult on introducing calorie labelling on menus in restaurants, cafes and takeaways, so families are clear about what they are consuming.