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School-Based Intervention to Decrease Consumption of Soda Has Modest Effect at Decreasing Number of Overweight and Obese Children


  • In overweight and obese school age children, can a school based education program aimed at reducing consumption of carbonated beverages prevent excessive weight gain?

Clinical Bottom Lines

  1. There is a 7.7% decrease in the number of obese children, defined as BMI >91st %, after one year in classes who undergo an education based program to reduce the number of carbonated beverages.
  2. There is no significant change after one year in the difference of body mass index when comparing classes that did and did not undergo the educational program.

Summary of Key Evidence

  1. 644 children ages 7-11 from southwest England divided into 29 clusters.1
  2. Clusters randomized to intervention and control groups.
  3. Primary author delivered a program to the intervention groups to discourage consumption of "fizzy" drinks and promote a balanced, healthy diet. Program focused on a simple, uncomplicated message to "ditch the fizz". Took place over 4 one-hour sessions (one per term) throughout one school year.
  4. Anthropometric measurements taken at 0, 6, and 12 months. Weight and height converted to BMI.
  5. The outcome was BMI for each cluster.
  6. After 12 months, there was no significant change in the difference in mean BMI between the two groups (18.3 in control clusters vs. 17.9 in intervention group (mean difference 0..4; 95%CI:0.2 to 1.0)).
  7. The mean percentage of overweight and obese children increased in the control group by 7.5%, and decreased in the intervention group by 0.2% (mean difference 7.7%; 95%CI:2.2% to 13.1%).
  8. Results suggest that education about extra calories consumed from carbonated beverages can result in decrease rates of obesity.
  9. Possibility of harm is minimal.
  10. Limitations of the study include: relatively low statistical power (n=29); randomization was not concealed; and, randomization occurred by class, which may have allowed transfer of the educational message outside of the classroom.

Additional Comments

  • Rates of childhood obesity are rising and implications will be far reaching.
  • Theoretically, daily consumption of one can of a sweetened carbonated drink over a 10 year period in a constant environment can add 50 kg of weight.2
  • Majority of efforts to decrease rates of childhood obesity have not been proven effective.
  • One of the only pediatric trials published to date where a simple intervention resulted in a significant decrease in the prevalence of obesity.


  1. James J, Thomas P, Cavan P, Kerr D. Preventing childhood obesity by reducing the consumption of carbonated drinks: cluster randomized controlled trial. BMJ 2004; 328: 1237-1241.
  2. Ebbeling CB, Pawlak DB, Ludwig DS. Childhood obesity: public-health crisis, common sense cure. Lancet 2003; 360:473-482.

CAT Author: Laura Walls, MD

CAT Appraisers: Alex Kemper , MD

Date appraised: April 19, 2006

Last updated November 28, 2006
Department of Pediatrics and Communicable Diseases
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