Obesity is an excess of body fat. A direct measurement of body fat cannot be done easily. So the working definition of obesity is a body mass index (BMI) greater than 30. BMI is more accurate than using simply body weight because BMI uses both height and weight to determine the number.
Obesity rates in the United States and around the world are rising. Obesity affects both adults and children.
Approximately 9 million (about 15%) of American children aged 6 to 17 are obese, a percentage that has doubled since the 1960s.
Obesity can shorten your life and put you at risk of developing a number of conditions, such as
high blood pressure,
diabetes,
heart disease and some forms of
cancer. Many other health risks are higher for people who are obese, and the risks may increase as the degree of obesity increases. People who carry extra weight around their waist, rather than in their legs and thighs, may be more likely to experience health problems caused by obesity.
People become obese for a number of reasons. Often, several of these factors are involved. Some of the most common reasons for obesity are :
- Genetic influences. Your genetic makeup plays a significant role in how likely it is that you will become obese. However, you still maintain most of the control when it comes to your weight, unless you have one of some rare genetic diseases that make it almost impossible to avoid obesity.
- Physiological influences. Some researchers believe that every person has a specific set point for body weight a predetermined weight that the body resists moving away from. Also, people of the same age, sex and body size often have different metabolic rates, meaning their bodies burn food differently. Someone with a low metabolic rate may require fewer calories to maintain approximately the same body weight as someone whose metabolic rate is high.
- Food intake and eating disorders. If you eat a lot, especially foods that are high in fat and calories, you can become obese. Obesity also can result from eating disorders, such as night-eating syndrome or a tendency to binge.
- Lifestyle. If you lead a sedentary life, in which you sit most of the time and do not exercise, you are at a higher risk of becoming obese.
- Your weight history. If you were overweight as a child or as an adolescent, you are more likely to be obese as an adult.
- Pregnancy. Pregnancy can contribute to obesity. About 15% of women weigh 20 pounds more after each pregnancy.
- Drugs. Some drugs can cause obesity. The most common drugs associated with obesity are steroid hormones and many of the drugs used to treat psychiatric conditions.
