Children and Youth with Obesity—a growing global epidemic


According to the US Centers for Disease Control (CDC), obesity has more than doubled in children and quadrupled in adolescents in the last 30 years.1 In 2012, more than a third of children and adolescents in the US were overweight or obese.1 Obesity is not limited to developed countries or older children, the World Health Organization (WHO) estimated that in 2013, 42 million children under the age of 5 years were overweight and close to 31 million of these children were living in developing countries.2 The global nature and steady increase has led the WHO to declare childhood obesity as “one of the most serious public health challenges of the 21st century.”2

Obesity can have wide ranging effects both in the short-term and long-term. In the short term, it can affect social, psychological and physical health. For example, children and adolescents with obesity are more likely to have cardiovascular risk factors, pre-diabetes, bone and joint problems, sleep apnea, stigmatization and poor self-esteem.1 In the long-term, children and youth with obesity are more likely to grow up to be adults with obesity, which increases the risk for a number of chronic conditions including heart disease, stroke, diabetes, osteoarthritis, and many forms of cancer.1

According to the CDC, the cause of obesity is quite simple: caloric imbalance.1 That means “too few calories are expended for the amount of calories consumed.” This can be “affected by genetic, behavioral, and environment factors.” 1 Many prevention and treatment programs aim to address this caloric imbalance through increased physical activity and healthy eating.

These aims appear straightforward; however, the growing epidemic, the volume of research, and the number of complex programs to address the problem highlight that these goals are difficult to achieve. There are two general approaches to many public health problems—prevention and treatment. As a starting point, we examine the evidence on preventing obesity in children and youth.

A Cochrane review examined 55 comparative studies conducted in countries around the globe.3 Most of the studies involved children between the ages of 6 and 12 years. The authors found that many programs improved nutrition and physical activity, and a meta-analysis of 37 studies with 27,964 children showed an overall significant reduction in adiposity (a measure of body fat). However, there was a very wide range of effects across the programs, with some programs on their own not showing an effect.

The authors indicated that the results of the review should be interpreted cautiously. They suggested that the results may be biased as the review may have missed small studies with negative findings. Further, there was little information available on the long-term impact of these programs. Finally, the evidence did not allow us to understand which components within the different programs may have the greatest effect on preventing obesity in children.

On a positive note, the authors did not find any harms associated with the interventions, such as unhealthy dieting practices or body image. Further, the authors were able to tease out the following “promising policies and strategies”:

  • “school curriculum that includes healthy eating, physical activity and body image
  • increased sessions for physical activity and the development of fundamental movement skills throughout the school week
  • improvements in nutritional quality of the food supply in schools
  • environments and cultural practices that support children eating healthier foods and being active throughout each day
  • support for teachers and other staff to implement health promotion strategies and activities (e.g. professional development, capacity building activities)
  • parent support and home activities that encourage children to be more active, eat more nutritious foods and spend less time in screen based activities.”3

Dr. Geoff Ball, Director of the Pediatric Centre for Weight and Health at the Stollery Children’s Hospital in Edmonton, Alberta, works with children aged 2 to 17 and their families on a regular basis and offers the following perspective:

When ‘success’ in treating or managing obesity is defined based on weight status, the effects of most lifestyle and behavioral interventions are modest. This reality highlights two points:

  1. The health and well-being of children should be defined using a number of different metrics. Weight status, usually determined using the body mass index (BMI) percentile or z-score, is one of several indicators that can include data regarding lifestyle habits (e.g., dietary quality, physical activity, sedentary behaviors) and psychosocial health (e.g., self-esteem, quality of life).
  2. ‘Upstream’ initiatives that promote and support healthy lifestyle habits and cognitions to prevent unhealthy weight gain are needed for the primary prevention of childhood obesity.

In addition, most strategies to prevent obesity in children have their genesis in health care and education settings. More recently, initiatives that take a broader perspective of preventing obesity have included communities, municipalities and other jurisdictions (provinces, states, nations) that have key roles to play in setting policies that influence everything from community zoning bylaws (that influence the location and availability/quality of grocery stores and sidewalks, respectively) to agricultural subsidies of some foods over others to food labeling policies that influence the information consumers have access to at the point-of-purchase in restaurants and grocery stores. The current ‘big picture’, systems view of obesity highlights the complexity and inter-relatedness of the causes and consequences of unhealthy weight gain. The old axiom ‘eat less and move more’ may be a catchy phrase, but it fails to acknowledge the most up-to-date perspective on obesity (prevention and management) as a chronic condition that requires long-term, multi-sector strategies in order to enable healthy lifestyle choices in healthy environments for healthy families.

Child playing outside

Source: Wikimedia Commons


References & Resources:

  1. Centers for Disease Control and Prevention. Childhood Obesity Facts.
  2. World Health Organization. Childhood overweight and obesity.
  3. Waters E, de Silva-Sanigorski A, Burford BJ, Brown T, Campbell KJ, Gao Y, Armstrong R, Prosser L, Summerbell CD. Interventions for preventing obesity in children. Cochrane Database of Systematic Reviews 2011, Issue 12. Art. No.: CD001871. DOI: 10.1002/14651858.CD001871.pub3. See summary here.
  • Preventing Childhood Obesity: Tips for Parents and Caretakers (2015). American Heart Association webpage


Obesity Prevention | Cochrane Child Health Twitter Journal Club – #CochraneChild

Thanks to everyone for joining the #CochraneChild Twitter journal club on March 25th, 2015. The archived discussion is at

What: Twitter journal club on interventions for preventing obesity in children

When: Wednesday, March 25th, 2:00pm Vancouver | 3:00pm Edmonton & Calgary | 5:00pm Toronto | 9:00pm United Kingdom | 8:00am Thursday March 26th, Melbourne, Australia

Where: Follow #CochraneChild on Twitter and join in the discussion by including #CochraneChild in all your posts. See these tips for participating in a Twitter chat.

Link to paper: Interventions for Preventing Obesity in Children

Questions we will be addressing:

1. The concept of ‘prevention’ is a struggle. With most of the included studies being short-term, is obesity being ‘prevented’?
2. Most studies were conducted in schools. What have we learned since 2010/11 about prevention in non-school settings?
3. It’s unclear how intervention intensity impacted outcomes. Beyond program duration, is there a way to capture that metric?
4. Any evidence on the differential impact of prevention programs based on weight status (e.g., overweight/obese vs healthy weight)?

Our guest host for the journal club is Dr. Geoff Ball

Geoff Ball

Geoff Ball


Geoff Ball is the Founding Director of the Pediatric Centre for Weight and Health, an inter-professional obesity management clinic at the Stollery Children’s Hospital in Edmonton, AB. His research program in the Department of Pediatrics (University of Alberta) applies a number of research methods, including clinical trials, qualitative inquiry, epidemiology, and literature reviews that are designed to generate, translate, and apply new knowledge that can optimize obesity management and prevention for children, youth, and families.