Methods

National obesity epidemic

Individuals gain excess weight when they consume more energy each day than their bodies need to support their physical activity and basic bodily functions (and, in children, their healthy growth).

Adults in the US currently consume, on average, about 220 more calories each day than they actually need to maintain a healthy weight.1 Children and youth are consuming about 200 calories per day beyond what they need for healthy growth (with smaller excess at younger ages).2

Consuming small amounts of extra calories on a daily level promotes weight gain over time.

Childhood obesity

Average BMI among US youth has increased by 0.5 per decade since the early 1970s; average youth weight increased by 1.5 kg per decade. If these trends continue, by 2020 the average US child will be 1.8 kg heavier than a child of the same age in 2007–2008. More than one in five children will be obese.

Stopping the rising trend in body weight would require eliminating an average of 41 kcal/day per child. Reversing the trend and reaching the Healthy People goals by 2020 would require an additional reduction of 23 kcal/day per child (Healthy People 2020 goal). Reaching the previous, more ambitious Healthy People 2010 goals would require much larger changes.3,2

Preventing weight gain at an earlier age through small decreases in energy intake and increases in energy expenditure is more achievable than attempts to lose weight once a child has already become obese.

A framework for action

Translating the obesity epidemic into age-specific energy gaps makes it possible to work with a range of stakeholders across multiple settings where children spend their lives, in order to identify policy and program changes that can cumulatively close the energy gap.

The Childhood Obesity Intervention Cost-Effectiveness Study (CHOICES) is working to identify the most cost-effective policy and programmatic interventions that can contribute to eliminating the energy gap and reversing the childhood obesity epidemic.

CHOICES’ methods include:

  • Working with researchers and key stakeholders to identify the most promising programs and policies for evaluation: Stakeholder consultation
  • Building a computer model of the US population and projecting Body Mass Index (BMI) changes and health outcomes over time: US population model
  • Synthesizing scientific literature to estimate the likely effects of promising obesity prevention interventions on BMI and physical activity: Systematic reviews and meta-analyses
  • Integrating information on the economic costs and health effects of interventions, utilizing a structured, transparent process: Cost-effectiveness analysis

References

1. Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011 Aug 27;378(9793):826-37. doi: 10.1016/S0140-6736(11)60812-X.
Open access (with free registration): http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2811%2960812-X/abstract

2. Hall KD, Butte NF, Swinburn BA, Chow CC. Dynamics of childhood growth and obesity: development and validation of a quantitative mathematical model. Lancet Diabetes Endocrinol. 2013 Oct;1(2):97-105. Abstract: http://www.thelancet.com/journals/landia/article/PIIS2213-8587%2813%2970051-2/abstract

3. Wang YC, Orleans CT, Gortmaker SL. Reaching the healthy people goals for reducing childhood obesity: Closing the energy gap. Am J Prev Med. 2012 May;42(5):437-44. doi: 10.1016/j.amepre.2012.01.018.
Open access: http://www.ajpmonline.org/article/S0749-3797(12)00075-X/fulltext