The Childhood Energy Gap

Dates of Project: November 2004–July 2013

Description: A team of researchers led by a Harvard School of Public Health professor and a Columbia University associate professor developed and used statistical models and related modeling techniques to analyze factors contributing to the nation’s increase in childhood obesity and to identify promising interventions to reverse the trend.

More specifically, the researchers focused on quantifying and reducing the youth population’s energy imbalance or gap—that is, the number of calories taken in daily through food and drink in excess of the number needed to support physical activity, normal growth, and body function.

The project also included formation and support of a collaborative network of childhood obesity modelers in Canada, England, and Australia as well as the United States.

Key Findings

  • As published in the journals cited below:

    • Over a 10-year period U.S. children and adolescents overall experienced an energy gap of roughly 110 to 165 calories per capita per day, on average.
    • U.S. overweight adolescents consumed an average of 700 to 1,000 more calories a day than required for normal growth, physical activity, and body function.
    • Based on past trends, the average weight of U.S. children and adolescents will increase almost four pounds by 2020 compared to 2007-2008, and more than one in five children will be obese. To avert that increase, youth age 2-19 would have to reduce their energy gap by an average of 41 calories per day.
    • To achieve the federal government’s Healthy People 2020 obesity-reduction goal, youth would have to eliminate an additional 23 calories per day on average—for a total daily reduction of 64 calories per day.
    • Children and adolescents age 2-19 increased their caloric contribution from sugar-sweetened beverages and 100-percent fruit juice from 242 calories a day in the period 1988–1994 to 270 calories a day in 1999–2004.
    • Youth now get 10 percent to 15 percent of their total calories from sugar-sweetened beverages and 100-% fruit juice.
    • If schools replaced all sugar-sweetened drinks with water (and students did not make up the loss by intake elsewhere), the energy gap would decline by 12 calories a day.
    • Participation in a comprehensive physical education program could increase energy expenditure by about 19 calories a day among children age 9 to 11. For grades kindergarten through 5th, an afterschool program could increase students’ energy expenditures by 25 calories a day.


Wang YC, Gortmaker SL, Sobol AM, and Kuntz KM. "Estimating the Energy Gap Among US Children: A Counterfactual Approach." Pediatrics, 118(6): e1721–e1733, 2006. Full text available online.

Wang YC, Orleans CT, and Gortmaker SL.  “Reaching the Healthy People Goals for Reducing Childhood Obesity: Closing the Energy Gap.” American Journal of Preventive Medicine, 42(5): 437–444, 2012. Abstract online.

Wang YC, Bleich SN, and Gortmaker SL. “Increasing Caloric Contribution from Sugar-sweetened Beverages and 100% Fruit Juices among US Children and Adolescents, 1988–2004.” Pediatrics, 121(6): e1604–e1614, June 2008. Abstract online.

Key Results

  • As published in the journal articles cited below:

    • A caloric calculator created by team members provides educators, parents, and other stakeholders with a user-friendly tool to assess the potential of a range of childhood obesity-prevention strategies.
    • The project created and expanded an international network of researchers using computational and statistical modeling to evaluate the effect of interventions and policies that impact the prevalence of childhood obesity.


Wang YC, McPherson K, Marsh T, Gortmaker SL, and Brown M. “Health and Economic Burden of the Projected Obesity Trends in the USA and the UK.” Lancet, 378(9793): 815–825, August 2011. 

Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, and Swinburn BA. “Quantification of the Effect of Energy Imbalance on Bodyweight.” Lancet, 378(9793): 826–837, August 2011. 

Swinburn BA, Sacks G, Hall KD, McPherson K, Finegood DT, Moodie ML, and Gortmaker SL. “The Global Obesity Pandemic: Shaped by Global Drivers and Local Environments.” Lancet, 378(9793): 804–814, August 2011.

Gortmaker SL, Swinburn BA, Levy D, Carter R, Mabry PL, Finegood DT, Huang T, Marsh T, and Moodie ML. “Changing the Future of Obesity: Science, Policy, and Action.” Lancet, 378(9793): 838–847, August 2011.

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A caloric calculator can assess the potential of a range of childhood obesity-prevention strategies.