Why Children and Teens Become Obese or Severely Overweight
Causes of Childhood Obesity
Obesity in children and teens (meaning a BMI-for-age above the 95th percentile) can occur as a result of different combinations of reasons, including environmental and genetic factors. However, it’s important to realise that weight gain, whether leading to mild or severe clinical obesity, typically occurs only when a person consumes more calories than he/she expends. A large calorie surplus is typically needed to cause obesity.
Environmental Causes of Child Obesity
- Insufficient Calorie Expenditure Through Exercise
The average American child spends a significant percentage of leisure time watching TV, or playing computer games. Few calories are expended during this sedentary activity. Not surprisingly, obesity rates are higher among children and teenagers who frequently watch television. In addition, only a small minority of children (1 in 5) regularly participate in after-school sports or extra-curricular physical activity.
- Excessive Snacking
Excess nibbling is a probable cause of obesity in children. Americans are estimated to spend over $1 billion dollars a day on snacks. The average American eats the equivalent of a fourth meal every day. And children are no exception. Often surrounded at school by high-calorie snack vending machines dispensing (eg) sugary soft drinks, regular TV-watching exposes the child to a battery of high-energy snack foods and drinks.
- Fast Food Diet
Over-consumption of fast food is another probable cause of child/teen obesity. In 1992, children aged 6-14 years ate in quick-serve restaurants on average 157 million times a month. Children are courted and targeted by many fast food chains, who promote super-size portions and all-you-can-eat offers.
- Family Behaviors
It’s difficult to separate genetic from family-environmental factors as causes of childhood obesity. Although children of obese parents are estimated to have a 25-30 percent extra chance of becoming obese themselves, part of this increased risk of obesity is probably due to eating habits and poor family nutrition, rather than heredity. Parental behavioral patterns concerning shopping, cooking, eating and exercise, have an important influence on a child’s energy balance.
- Body Image
Obesity in a child or adolescent may also be encouraged by a distorted body image, due to peer pressure, parental influence – including attitude of parents to weight loss and dieting.
Genetic Causes of Child Obesity
Genes affect a huge number of weight-related chemical processes in the body. Metabolic rate, blood glucose metabolism, fat-storage, hormones to name but a few, are all influenced by our genetic inheritance. Also, some studies of adopted children indicate that adopted children tend to develop weight problems similar to their biological, rather than adoptive, parents. In addition, infants born to overweight moms have been found to be less active and to gain more weight by the age of three months when compared with infants of normal weight mothers. This indicates a possible inborn drive to conserve energy (Roberts, Savage, Coward, Chew, & Lucas, 1988).
Genes Cannot Account For Surge in Child Obesity
Although genes do have an effect on weight-related chemical processes in children, they cannot account for the sudden upsurge in childhood obesity, or the rise in teenage obesity. Approximately one in five children in the US between the ages of 6 and 17 is overweight. This is twice the rate it was, 30 years ago. By contrast, changes in genes and DNA only occur over thousands of centuries.