Obesity is a complex disease for which no single cause or cure exists. You gain weight when you take in more calories than you burn off. But obesity is influenced by many other factors, also: your family history, the type of work you do, your race, and your environment.

Overeating is easy in our culture today. Portions at fast-food and other restaurants are "supersized" to the point that one meal can provide an entire day's worth of calories. Food is also a focal point of social activity. Gatherings of family and friends, work events, and holidays are usually centered around food. And eating can be a comfort when you are depressed or stressed.

Next, people are less active than ever. Some people hate to exercise and others may not have the time. Also, many of the conveniences we use, such as the remote control for the television, elevators, and cars, cut activity out of our lives.

Even making small changes-like walking your dog-can make a difference. Letting the dog out the door burns 2 calories. Walking the dog for 30 minutes burns 125 calories. Taking the car to a car wash uses 18 calories. Washing and waxing it yourself burns 300.

Use this interactive tool to find out how many calories you burn with typical daily activities and exercise:

Interactive Tool: Calories Burned

Other things can affect our weight, such as family history or genetics. If one of your parents is obese, you are 3 times as likely to be obese as someone with parents of healthy weight.³

Your family's and friends' lifestyles can also affect your weight. If your family or friends eat a lot of high-fat or snack foods, eat at irregular times, and skip meals, you probably will too. And if they are not physically active, you may not be either.

Other things influence your weight and whether you are physically active, including:

• Low self-esteem. Being overweight or obese may lower your self-esteem and lead to eating as a way to comfort yourself. Repeated failure at dieting also can affect your self-esteem and make it even more difficult to lose weight.
• Emotional concerns. Emotional stress, anxiety, or illnesses such as depression or chronic pain can lead to overeating. Some people eat to calm themselves, to avoid dealing with unpleasant tasks or situations, or to dampen negative emotions.
• Trauma. Distressing events, such as childhood sexual, physical, or emotional abuse; loss of a parent during childhood; or marital or family problems, can contribute to overeating.
• Alcohol. Alcohol (beer and mixed drinks) is very high in calories. Drinking alcohol may cause you to gain more weight around your stomach.
• Medicines or medical conditions. Some medical conditions and medicines may also cause weight gain. Examples include having Cushing's syndrome or hypothyroidism or taking antidepressants or corticosteroids.