Although there are some genetic or hormonal causes of childhood obesity, in most cases excess weight is due to overeating and under-exercising. Children require extra calories to fuel their growth and development; if they taken in the appropriate amount of calories, they should add pounds in proportion to their growth. But if they consume more calories than they’re burning off, the result will be unnecessary weight gain. Childhood obesity is almost always a result of a number of factors working together to increase risk.  These include:

Diet: Unhealthy lunch options and regular consumption of high-calorie foods, like fast food, cookies and other baked goods, soda, candy, chips and vending machine snacks contribute to weight gain. Snacking is another major culprit: new research shows that American children are snacking more than ever before -- sometimes almost continuously throughout the day -- accounting for up to 27% of their daily caloric intake. Between 1977 and 2006, children increased their caloric intake from snacks by an average of 168 calories/day, up to a total of 586 calories. The largest increase was found in children aged 2 to 6, who consumed an extra 181 snack calories per day compared to two decades earlier.

Lack of physical activity: Computers, television, and video games conspire to keep kids inside and sedentary, which means they burn fewer calories and are more likely to gain weight. Concerns about the safety of outside play and a reliance on cars instead of walking – even to the corner store – don’t help matters. By preschool age, many kids are already lacking enough activity, which often translates into poor exercise habits later in life.

Questionnaire: Is your young child active enough?

Questionnaire: Is your older child active enough?

Environment: If a child opens up the refrigerator or kitchen cabinets and is greeted by bags of chips, candy bars and microwave pizza, then that’s likely what they will eat. Similarly, if you keep your fridge stocked instead with tasty cut-up fruits and veggies (berries, baby carrots, red pepper strips) with low-fat ranch dip, low-fat yogurt and higher-fiber granola bars, then they will go for the healthier fare (rather than eat nothing at all). Don’t feel like you need to deny children all treats, but strive for a healthy balance.

Psychological factors: Like adults, some kids may turn to food as a coping mechanism for dealing with problems or negative emotions like stress, anxiety, or boredom.  Children struggling to cope with a divorce or death in the family may eat more as a result.

Genetics: If your child was born into a family of overweight people, he/she may be genetically predisposed to the condition, especially if high-calorie food is readily available and physical activity is not encouraged.

Socioeconomic factors: Children from low-income backgrounds are at increased risk for childhood obesity since low-income parents may lack the time and resources necessary to purchase and prepare healthy foods (versus fast food, which is cheaper and more readily available in low-income communities), join a gym or otherwise encourage physical activity. Because safety is a big issue in poorer communities, playing outdoors may not be a viable option.

Medical conditions: Though not common, there are certain genetic diseases and hormonal disorders that can predispose a child to obesity, such as hypothyroidism, (when the thyroid gland, located in the neck just below the voice box, is underactive and does not release enough of the hormones that control metabolism), Prader-Willi syndrome (a genetic disorder affecting the part of the brain that controls feelings of hunger)  and Cushing's syndrome (a disorder in which your body is exposed too much of the hormone cortisol from overproduction in the adrenal glands or use of medications such as those for asthma).

Sleep: In a review of studies in the journal Archives of Disease in Childhood, researchers found that kids who sleep less than the recommended amount of about 13 hours a day at age 2 are more likely to be obese at age 7. One reason: Fatigue alters the levels of appetite-regulating hormones [http://www.parenting.com/article/Pregnancy/Behavior/A-Surprising-Cause-of-Child-Obesity], which can cause children to eat more.