Childhood obesity has been called “one of the most serious public health challenges of the 21st century,” and with good reason. (1)
Obesity can harm nearly every system in a child’s body—heart and lungs, muscles and bones, kidneys and digestive tract, as well as the hormones that control blood sugar and puberty—and can also take a heavy social and emotional toll. (2) What’s worse, youth who are overweight or obese have substantially higher odds of remaining overweight or obese into adulthood, (3) increasing their risk of disease and disability later in life.
Globally, an estimated 43 million preschool children (under age 5) were overweight or obese in 2010, a 60 percent increase since 1990. (4) The problem affects countries rich and poor, and by sheer numbers, places the greatest burden on the poorest: Of the world’s 43 million overweight and obese preschoolers, 35 million live in developing countries. By 2020, if the current epidemic continues unabated, 9 percent of all preschoolers will be overweight or obese—nearly 60 million children. (4)
Obesity rates are higher in adults than in children. But in relative terms, the U.S., Brazil, China, and other countries have seen the problem escalate more rapidly in children than in adults. (5)
Of course, some regions still struggle mightily with child hunger, such as Southeastern Asia and sub-Saharan Africa. (6) But globalization has made the world wealthier, and wealth and weight are linked.
As poor countries move up the income scale and switch from traditional diets to Western food ways, obesity rates rise. (7) One result of this so-called “nutrition transition” is that low- and middle-income countries often face a dual burden: the infectious diseases that accompany malnutrition, especially in childhood, and, increasingly, the debilitating chronic diseases linked to obesity and Western lifestyles.
It’s surprisingly challenging to track childhood obesity rates across the globe. Many countries do not field nationally representative surveys that measure heights and weights of school-aged children, or don’t have repeated consistent measurements over time. Dueling definitions of childhood obesity—from the U.S. Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), and the International Obesity Task Force (IOTF)—further complicate matters, making it hard to compare data between regions.
Over the past three decades, childhood obesity rates have tripled in the U.S., and today, the country has some of the highest obesity rates in the world: one out of six children is obese, and one out of three children is overweight or obese. (8) Though the overall U.S. child obesity rate has held steady since 2008, some groups have continued to see increases, and some groups have higher rates of obesity than others:
- In the 1970s, 5 percent of U.S. children ages 2 to 19 were obese, according to the CDC’s current definition; by 2008, nearly 17 percent of children were obese, a percentage that held steady through 2010. (8,9)
- Obesity is more common in boys than girls (19 percent versus 15 percent). (8)
- Obesity rates in boys increased significantly between 1999 and 2010, especially among non-Hispanic black boys; but obesity rates in girls of all ages and ethnic groups have stayed largely the same. (8)
- Hispanic (21 percent) and non-Hispanic black (24 percent) youth have higher rates of obesity than non-Hispanic white youth (14 percent), a continuing trend. (8)
- Nearly 10 percent of U.S. infants had a high “weight for recumbent length”—a measure that’s similar to the body mass index but used in children from birth to age 2. (8)
- From 1999 to 2010, Mexican American infants were 67 percent more likely to have a high weight for recumbent length than non-Hispanic white infants. (8)
Canada has also seen a rise in childhood obesity since the late 1970s—overall, obesity rates have more than doubled, and in some age groups, tripled. (10) But childhood obesity rates are still a good bit lower there than they are in the U.S. In 2007–2008, nearly 9 percent of Canadian youth ages 6 to 17 were obese, based on the IOTF age-specific cutoffs. (10) Child obesity is a bigger problem among Canada’s Aboriginal groups: A survey of Aboriginal groups who live outside of reservations found that in 2006, nearly 33 percent of children ages 6 to 8 were obese, as were 13 percent of children ages 9 to 14. (10)