Obesity is a term used to describe body weight that is much greater than what is considered healthy. If you are obese, you have a much higher amount of body fat than is healthy or desirable.

Adults with a body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) greater than 25 kg/m² but less than 30 kg/m² are considered overweight.

Adults with a BMI greater than 30 kg/m² are considered obese.

Anyone who is more than 100 pounds overweight or who has a BMI greater than 40 kg/m² is considered morbidly obese.

Consuming more calories than you burn leads to being overweight and, eventually, obesity. The body stores unused calories as fat. Obesity can be the result of:

• Eating more food than your body can use
• Drinking too much alcohol
• Not getting enough exercise

An underactive thyroid (hypothyroidism) may lead to weight gain, but usually only 5 - 10 pounds of weight. Some antidepressants and antipsychotic medicines may also contribute to weight gain and obesity. Genetic factors play some part in the development of obesity -- children of obese parents are 10 times more likely to be obese than children with parents of normal weight.

People who are at higher risk for obesity include:

• Lower income groups
• Former smokers
• People with chronic mental illness
• People with disabilities
• People with a sedentary lifestyle