Obesity

I

Introduction

Obesity, medical condition characterized by storage of excess body fat. The human body naturally stores fat tissue under the skin and around organs and joints. Fat is critical for good health because it is a source of energy when the body lacks the energy necessary to sustain life processes, and it provides insulation and protection for internal organs. But the accumulation of too much fat in the body is associated with a variety of health problems. Studies show that individuals who are overweight or obese run a greater risk of developing diabetes mellitus, hypertension, coronary heart disease, stroke, arthritis, and some forms of cancer.

II

Measuring Obesity

The body mass index (BMI) is commonly used to determine desirable body weights. BMI is a measure of an adult’s weight in relation to height, and it is calculated metrically as weight divided by height squared (kg/m²). People with a BMI of 25.0 to 29.9 are considered overweight and people with a BMI of 30 or above are considered obese.

Body mass index only provides a rough estimate of desirable weight, however. Physicians recognize that many other factors besides height affect weight. Weight alone may not be an indicator of fat, as in the case of a bodybuilder who may have a high BMI because of a high percentage of muscle tissue, which weighs more than fat. Likewise, a person with a sedentary lifestyle may be within a desirable weight range but have excess fat tissue. In general, however, the higher the BMI, the greater the risk for developing serious medical conditions.

III

Complications of Obesity

Obesity increases the risk of developing disease. According to the National Institute of Diabetes and Digestive and Kidney Diseases, the majority of heart disease cases in the United States are linked to excess body fat, and obese people are more than twice as likely to develop hypertension. The risk of medical complications, particularly heart disease, increases when body fat is distributed around the waist, especially in the abdomen. This type of upper body fat distribution is more common in men than in women.

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Obese women are at nearly twice the risk for developing breast cancer, and all obese people have a 42 percent higher chance of developing colorectal cancer. Almost 80 percent of patients with Type 2 diabetes mellitus, also known as noninsulin-dependent diabetes mellitus, are obese.

Obese people also experience social and psychological problems. Stereotypes about “fat” people often translate into discriminatory practices in education, employment, and social relationships. The consequences of being obese in a world preoccupied with being thin are especially severe for women, whose appearances are often judged against an ideal of exaggerated slenderness.

IV

Causes of Obesity

A calorie is the unit used to measure the energy value of food and the energy used by the body to maintain normal functions. When the calories from food intake equal the calories of energy the body uses, weight remains constant. But when a person consumes more calories than the body needs, the body stores those additional calories as fat, causing subsequent weight gain. Consuming about 3,500 calories more than what the body needs results in a weight gain of 0.45 kg (1 lb) of fat.

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