What Is Obesity? 

Obesity results from the excessive accumulation of fat that exceeds the body's skeletal and physical standards. According to the National Institutes of Health (NIH), an increase in 20 percent or more above your ideal body weight is the point at which excess weight becomes a health risk. A person is considered to be obese if he/she weighs at least 100 pounds over ideal body weight or has a body mass index (BMI) greater than 35. The BMI is a mathematical formula that factors a person’s height and weight in determining obesity.

Today, 127 million Americans, more than one-third of the adult population, are overweight, and 60 million are obese. An estimated 9 million of those are considered morbidly obese. A person is considered to be morbidly obese with a BMI of 40 or greater. Persons with a BMI of 40 or more or those with a BMI or 35 or more with serious health conditions may be candidates for a bariatric procedure such as gastric bypass surgery.

Morbid obesity is a crippling, chronic disease with devastating effects. Some of the medical complications include:

• Diabetes
• Heart problems (cardiovascular disease)
• High cholesterol
• High blood pressure (hypertension)
• Sleep apnea
• GERD (gastroesophageal reflux disease)
• Degenerative joint disease
• Higher risk of specific cancers
• Urinary stress incontinence
• Menstrual irregularities
• Risk of infertility
• Depression

What Causes Obesity?

Causes of obesity involve many factors. In scientific terms, obesity occurs when a person's calorie intake exceeds the amount of energy he or she burns. Many factors may contribute to this imbalance, including genetic, environmental, psychological, and other factors.

Genetic Factors

Obesity tends to run in families, suggesting that it may have a genetic cause. However, family members share not only genes, but also diet and lifestyle habits that may contribute to obesity. Separating these lifestyle factors from genetic ones is often difficult. Still, growing evidence points to heredity as a strong determining factor of obesity. In one study of adults who were adopted as children, researchers found that the weight of the adult subjects was closer to the weight of their biological parents than the weight of their adoptive parents. The environment provided by the adoptive family apparently had less influence on the development of obesity than the person's genetic makeup.

Nevertheless, people who feel that their genes have doomed them to a lifetime of obesity should take heart. Many people genetically predisposed to obesity do not become obese or are able to lose weight and keep it off.

Environmental Factors

Although genes are an important factor in many cases of obesity, a person's environment also plays a significant part. Environment includes lifestyle behaviors, such as what a person eats and how active he or she is. Americans tend to have high-fat diets, often putting taste and convenience ahead of nutritional content when choosing meals. In addition, sedentary lifestyles are second to none in contributing to obesity.

People can't change their genetic makeup, of course, but they can change what they eat and how active they are. Some people are able to lose weight and keep it off by:

• Learning how to choose more nutritious meals
• Replacing refined foods with whole foods
• Learning to recognize environmental cues (such as enticing smells) that may make them want to eat when they are not hungry
• Becoming more physically active
• Cutting down on portion sizes

Psychological Factors

Many people eat in response to negative emotions, such as boredom, sadness, or anger. While most overweight people have no more psychological disturbances than people at their normal weight, about 30 percent of the people who seek treatment for serious weight problems have difficulties with binge eating. During a binge-eating episode, people eat large amounts of food while feeling they can't control how much they are eating. Those with the most severe binge-eating problems are considered to have what is called binge-eating disorder. These people may have more difficulty losing weight and keeping the weight off than people without binge-eating problems. Some individuals will need special help, such as counseling or medication, to control their binge eating before they can successfully manage their weight.

Other Causes of Obesity

In some instances, there are rare illnesses that can cause obesity; these include hypothyroidism, Cushing's syndrome, and certain neurological problems that can lead to overeating. Certain drugs, such as steroids and some antidepressants, may cause excessive weight gain. A doctor can determine if a patient has any of these conditions, which are believed to be responsible for only about 1 percent of all cases of obesity.