Weight status in children is determined by body mass index (BMI)-for-age percentiles. This calculates a child's weight category based on their age and BMI. A child is deemed overweight if their BMI-for-age percentile is over 85% and deemed obese if it is over 95%.
There is no doubt that the main causes of childhood obesity are an unhealthy diet and lack of physical activity.
Amanda Staiano, PhD, co-chair of the Public Affairs Committee at The Obesity Society- the leading organization dedicated to the study of obesity - told Medical News Today:
"The availability of liquid calories and empty calories, combined with a deluge of fast food and junk food advertisements, have changed the way children eat. The majority of children fail to meet the recommended 60 minutes of daily physical activity and spend a huge amount of time sitting. The way we've structured our daily lives makes it hard for children to live healthily."
It is clear that lifestyle changes have had a significant impact on childhood obesity over the past 30 years. Children used to consume one snack a day, while 1 in 5 school-age children now eats up to six snacks a day.
Food and drink portion sizes are also bigger than they were 30 years ago. In the mid-1970s, a standard sugar-sweetened drink was 13.6 ounces, while it stands at 20 ounces today.
Furthermore, the Harvard School of Public Health in Boston, MA, state a child's daily calorie intake from sugary beverages rose by 60% between 1989-2008.
Although availability of junk food and drink has decreased in schools, the Centers for Disease Control and Prevention (CDC) state that more than half of middle and high schools in the US still offer them for purchase.
And the advertising industry, health care professionals believe, has not helped rates of childhood obesity, with past studies suggesting that children exposed to junk food commercials are more likely to become obese.
Levels of physical activity have also reduced over the past 3 decades. The CDC state that last year, only 29% of high school students participated in the recommended 60 minutes of exercise a day.
The CDC state that last year, only 29% of high school students participated in the recommended 60 minutes of exercise a day.
Gone are the days when children would run around and play for hours after school. Now, they are more likely to engage in sedentary behaviors, such as watching TV, playing computer games or using social media. Children now spend an average of 7.5 hours a day using entertainment media.
There are other factors that have been associated with the development of childhood obesity. Genetic disposition is one.
A 2012 study reported by Medical News Today discovered two gene variants that researchers claim increase the risk of childhood obesity. A more recent study by researchers from the University of Cambridge in the UK revealed that a gene mutation called KSR2 may cause obesity by causing continued hunger pangs.
But health care experts believe it is primarily unhealthy diets and lack of exercise that have caused rates of childhood obesity to soar. "Although heredity may explain some of the obesity epidemic, it does not justify the explosion we've had over the last 30 years," Dr. Whitfield told us.