Intended for healthcare professionals

Primary Care

Preventing childhood obesity by reducing consumption of carbonated drinks: cluster randomised controlled trial

BMJ 2004; 328 doi: (Published 20 May 2004) Cite this as: BMJ 2004;328:1237

This article has a correction. Please see:

  1. Janet James, diabetes development nurse (janet.james{at},
  2. Peter Thomas, professor of health care statistics and epidemiology2,
  3. David Cavan, consultant physician1,
  4. David Kerr, consultant physician1
  1. 1 Bournemouth Diabetes and Endocrine Centre, Royal Bournemouth Hospital, Dorset BH7 7DW
  2. 2 Institute of Health and Community Studies, Bournemouth University and Dorset Research and Development Unit, Poole Hospital
  1. Correspondence to: J James
  • Accepted 9 March 2004


Objective To determine if a school based educational programme aimed at reducing consumption of carbonated drinks can prevent excessive weight gain in children.

Design Cluster randomised controlled trial.

Setting Six primary schools in southwest England.

Participants 644 children aged 7-11 years.

Intervention Focused educational programme on nutrition over one school year.

Main outcome measures Drink consumption and number of overweight and obese children.

Results Consumption of carbonated drinks over three days decreased by 0.6 glasses (average glass size 250 ml) in the intervention group but increased by 0.2 glasses in the control group (mean difference 0.7, 95% confidence interval 0.1 to 1.3). At 12 months the percentage of overweight and obese children increased in the control group by 7.5%, compared with a decrease in the intervention group of 0.2% (mean difference 7.7%, 2.2% to 13.1%).

Conclusion A targeted, school based education programme produced a modest reduction in the number of carbonated drinks consumed, which was associated with a reduction in the number of overweight and obese children.


  • We thank the headmasters, teachers, parents, and children at the participating schools, William Askew for writing and producing Ditch the Fizz, Julia Knott for help with data entry, Ruth Angel for discussion and advice, and the staff of the Bournemouth Diabetes and Endocrine Centre for help with anthropometric measurements.

  • Contributors DK and JJ developed the original idea. JJ delivered the education programme, took the anthropometric measurements, and analysed the data. All authors contributed to writing the manuscript. PT provided statistical and methodological advice. DK directed the project; he will act as guarantor for the paper. DC obtained financial support.

  • Funding This project was funded from unrestricted educational grants from GlaxoSmithKline, Aventis, and Pfizer and from internal resources within Bournemouth Diabetes and Endocrine Centre. The external funding bodies had no input into protocol development, data collection, or analyses or interpretation. JJ received a research scholarship from the Florence Nightingale Foundation.

  • Competing interests DK and DC each had a child attending one of the schools involved in the Christchurch obesity prevention project in schools.

  • Ethical approval This study was approved by the East Dorset research and ethics committee.

View Full Text