Topic Editor: Jennifer Orlet Fisher, PhD, Temple University, Center for Obesity Research and Education, USA
Topic funded by: The Lawson Foundation
Obesity is characterized by an excessive accumulation of body fat resulting from an imbalance between energy intake and spending. The reduced need for being physically active in the contemporary way of life, combined with the availability of affordable high-calorie food, contributes to the creation of an environment that increases the risk of obesity (“obesogenic” environment) in developed countries and, increasingly, in the developing world. The prevalence of obesity rose in the last decades among all age groups, including young children. In 2010, about 42 million children under the age of five were estimated overweight or obese, of whom almost 35 million were from developing countries. Once thought naturally physically active, young children spend in fact 80% or more of their time being sedentary. Children are considered overweight when their body mass index (BMI: the weight in kilograms divided by the height in meters) falls between the 85th and 94th percentile in established charts, and obese when their BMI falls at the 95th percentile or more, adjusted for age and sex. It is estimated that almost 10% of children younger than two years are obese and that over 25% of children aged between 2 and 5 years are overweight in the U.S. Yet, these prevalence rates should be interpreted with caution due to the variance across the U.S populations. In low-income populations (e.g., Hispanic populations), the emergence of childhood obesity is highest and emerges most rapidly in the first few years of life.
Childhood obesity is associated with adult obesity, itself associated with hypertension, coronary artery disease, and diabetes. Obesity is very difficult to treat once developed and puts affected children at risk for lifelong health problems and reduced quality of life as well as social stigma and exclusion. Thus, the individual and social cost (e.g., health care) of obesity is a heavy one. The focus of childhood obesity research is on the causes and consequences of obesity, successful intervention programs, and effective prevention strategies.