Obesity is a chronic disease. Being overweight is defined as having a body mass index (BMI) of 25.0 to 29.9, while obesity is defined as having a BMI of 30.0 or above. For Asian Americans, overweight is defined as having a BMI between 23 and 29.9, and obesity is defined by a BMI of 30.0 or greater. Figure 01. Your body mass index (BMI) is a measurement that is derived from a calculation of your weight relative to your height. Your BMI correlates fairly well with the amount of total body fat that you have.
Being overweight or obese is hazardous to your health. In 1985, the US Surgeon General warned that as a result of being overweight or obese, 34 million Americans were at risk for developing heart disease, stroke, diabetes, and cancer. Since then, the numbers of Americans at risk has almost tripled. According to the 1998 National Heart, Lung, and Blood Institute report, over one-half of all Americans are now overweight or obese. Recent estimates attribute about 112, 000 deaths each year in the US to obesity, making it second only to cigarette smoking as a cause of death.
Medical disorders such as high blood pressure, high cholesterol levels, and gallbladder disease are associated with obesity. Obesity has been shown to increase the risk of developing high blood pressure, adult-onset diabetes, heart attack, stroke, degenerative joint disease of the back and knees, gallstones, and certain forms of cancer such as that of the breast, prostate, and colon. Obese women commonly can have infertility problems, irregular menstrual flow, and urinary incontinence.
The good news is that losing as little as 10% of your current weight will help to lower your risk of developing certain obesity-related diseases. One recent study, for instance, indicates that a modest loss of 5% to 10% of body weight can lower blood pressure and reduce your risk of developing diabetes.
Affected individuals should seek treatment through clinical programs provided by licensed health care professionals. Bariatric physicians are specialized in treating obesity and its related diseases. Treatment is also offered through nonclinical commercial enterprises such as Weight Watchers.
Figure 01. BMI calculator
Obesity is a chronic disease caused by an interaction between genes and the environment.
Obesity is caused by an energy imbalance that occurs when a person consumes more calories than he or she burns through physical activity. If you consume more calories than you burn, you will gain weight. Conversely, if you burn more calories than you consume, you will lose weight. Knowing that, why so many people consume more calories than they can burn is unknown. For most people, it isn't because of gluttony, lack of willpower, or laziness. Almost everyone who is overweight or obese has tried to lose weight, been temporarily successful, but failed to keep the lost weight and more from returning. Why is it so difficult to lose weight and keep it off? Scientists have only partial answers. They are still trying to sort out the complex interactions between genetic makeup and the environmental causes of obesity.
Obesity has a strong genetic component, and tends to run in families. Family members share not only genes, but also diet and lifestyle habits that can contribute to obesity. In one study of adults who were adopted as children, researchers found that the subjects' adult weights were closer to their biological parents' weights than their adoptive parents. Apparently, in that study genetic makeup had more influence on those person's adult weights than did the environment provided by the adoptive family. Some experts estimated that 60% of our obesity is caused by genetic makeup, and 40% is caused by environmental factors.
Environmental factors also play a significant role in causing obesity. The availability or lack of food, as well as economic status, are environmental factors that contribute to obesity. Environmental factors also include lifestyle behaviors such as what and how often you eat, and how active you are. Americans tend to like to eat a high-fat diet for reasons of taste and convenience. Also, many people, at least those in affluent industrialized countries, aren't physically active enough. Chronic sleep deprivation can also increase the risk of developing obesity.
Many people eat in response to negative emotions such as anger, boredom, or sadness. However, most overweight people have no higher rates of diagnosed psychological disorders than people of normal weight. Binge-eating disorder, and an eating disorder in which people overeat for psychological reasons, can lead to obesity.
Some prescription drugs and certain illnesses can cause or contribute to obesity. Hypothyroidism, Cushing's syndrome, and certain psychiatric and neurological problems can lead to weight gain. Certain drugs, including steroids and many medications used to treat psychiatric diseases such as depression, bipolar disorder, and schizophrenia, can cause excessive weight gain.
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