Obesity results from the excessive accumulation of fat that exceeds the body's skeletal and physical standards. Today 97 million Americans, more than one-third of the adult population, are overweight or obese. An estimated 5 to 10 million of those are considered morbidly obese. Obesity becomes "morbid" when it reaches the point of significantly increasing the risk of one or more obesity-related health conditions or serious diseases, also known as co-morbidities that result in significant physical disability or even death.

Causes of Obesity

In scientific terms, obesity occurs when a person consumes more calories than he or she burns. What causes this imbalance between calories in and calories out may differ from one person to another. Genetic, environmental, psychological, and other factors may all play a part.

Genetic factors:
Obesity tends to run in families, suggesting a genetic cause. Yet families also share diet and lifestyle habits that may contribute to obesity. Separating these from genetic factors is often difficult. Even so, science shows that heredity is linked to obesity. In one study, adults who were adopted as children were found to have weights closer to their biological parents than to their adoptive parents. In this case, the person's genetic makeup had more influence on the development of obesity than the environment in the adoptive family home.

Environmental factors:
Genes do not destine people to a lifetime of obesity, however. Environment also strongly influences obesity. This includes lifestyle behaviors such as what a person eats and his or her level of physical activity. Americans tend to eat high-fat foods, and put taste and convenience ahead of nutrition. Also, most Americans do not get enough physical activity. Although you cannot change your genetic makeup, you can change your eating habits and levels of activity. Try these techniques that have helped some people lose weight and keep it off:

• Learn how to choose more nutritious meals that are lower in fat.
• Learn to recognize and control environmental cues (like inviting smells) that make you want to eat when you're not hungry.
• Become more physically active.
• Keep records of your food intake and physical activity.

Psychological factors:
Psychological factors may also influence eating habits. Many people eat in response to negative emotions such as boredom, sadness, or anger. Most overweight people have no more psychological problems than people of average weight. Still, up to 10 percent of people who are mildly obese and try to lose weight on their own or through commercial weight loss programs have binge eating disorder. This disorder is even more common in people who are severely obese. During a binge eating episode, people eat large amounts of food and feel that they cannot control how much they are eating. Those with the most severe binge eating problems are also likely to have symptoms of depression and low self-esteem. These people may have more difficulty losing weight and keeping it off than people without binge eating problems. If you are upset by binge eating behavior and think you might have binge eating disorder, seek help from a health professional such as a psychiatrist, psychologist, or clinical social worker.

Other causes of obesity:
Some illnesses can lead to obesity or a tendency to gain weight. These include hypothyroidism, Cushing's syndrome, depression, and certain neurological problems that can lead to overeating. Also, drugs such as steroids and some antidepressants may cause weight gain. A doctor can tell whether there are underlying medical conditions that are causing weight gain or making weight loss difficult.


Body Mass Index

Everyone needs a certain amount of body fat for stored energy, heat insulation, shock absorption, and other functions. As a rule, women have more body fat than men. Most health care providers agree that men with more than 25 percent body fat and women with more than 30 percent body fat are obese. Because measuring a person's body fat is difficult, health care providers often rely on other means to diagnose obesity. Weight-for-height tables, which have been used for decades, usually have a range of acceptable weights for a person of a given height. One problem with these tables is that there are many versions, all with different weight ranges. Another problem is that they do not distinguish between excess fat and muscle. A very muscular person may appear obese, according to the tables, when he or she is not. In recent years, body mass index (BMI) has become the medical standard used to measure overweight and obesity. BMI uses a mathematical formula based on a person's height and weight. BMI equals weight in kilograms divided by height in meters squared (BMI = kg/m2). The BMI table that follows has already calculated this information. Although the BMI ranges shown in the table are not exact ranges of healthy and unhealthy weight, they are useful guidelines. A BMI of 25 to 29.9 indicates a person is overweight. A person with a BMI of 30 or higher is considered obese. Like the weight-to-height table, BMI does not show the difference between excess fat and muscle. BMI, however, is closely associated with measures of body fat. It also predicts the development of health problems related to excess weight. For these reasons, BMI is widely used by health care providers.

Calculate your BMI


Consequences of Obesity

Weight loss is not a cure for eating disorders. And there are medical conditions, such as hyperthyroidism, that can also cause weight gain. It's important to work with your doctor to make sure that you do not have a condition that should be treated with medication and counseling.

Co-morbidities are health conditions, which whether alone or in combination, can significantly reduce your life expectancy. A partial list of common conditions follows.

• Diabetes: Obese individuals develop a resistance to insulin, which regulates blood sugar levels. Over time, the resulting high blood sugar can cause serious damage to the body.
• High blood pressure/Heart disease: Excess body weight strains the ability of the heart to function properly. The resulting hypertension (high blood pressure) can result in strokes, as well as inflict significant heart and kidney damage.
• High cholesterol: Elevation of lipids and triglycerides in the blood, which contributes to early heart disease, blood vessel disease and stroke.
• Sleep apnea/Respiratory problems: Fat deposits in the tongue and neck can cause intermittent obstruction of the air passage. Because the obstruction is increased when sleeping on your back, you may find yourself waking frequently to reposition yourself. The resulting loss of sleep often results in daytime drowsiness and headaches.
• Gastroesophageal reflux/Heartburn: Acid belongs in the stomach and seldom causes any problem when it stays there. When acid escapes into the esophagus through a weak or overloaded valve at the top of the stomach, the result is called gastroesophageal reflux, and heartburn and acid indigestion are common symptoms. Approximately 10-15% of patients with even mild sporadic symptoms of heartburn will develop a condition called Barrett's esophagus, which is a pre-malignant change in the lining membrane of the esophagus, a cause of esophageal cancer.
• Osteoarthritis of weight-bearing joints: The additional weight placed on joints, particularly knees and hips, results in rapid wear and tear, along with pain caused by inflammation. Similarly, bones and muscles of the back are constantly strained, resulting in disk problems, pain and decreased mobility.
• Gallbladder disease: The formation of gallstones within the gallbladder, which can lead to symptoms of severe abdominal pain, nausea and vomiting.
• Menstrual irregularities: Morbidly obese individuals often experience disruptions of the menstrual cycle, abnormal menstrual flow and increased pain associated with the menstrual cycle.
• Infertility/Pregnancy complications: The inability or diminished ability to produce offspring or maintain a healthy pregnancy.
• Urinary stress incontinence: A large, heavy abdomen and relaxation of the pelvic muscles, especially associated with the effects of childbirth, may cause the valve on the urinary bladder to be weakened, leading to the leakage of urine with coughing, sneezing or laughing.
• Depression: Seriously overweight persons face constant challenges to their emotions: repeated failure with dieting, disapproval from family and friends, sneers and remarks from strangers. They often experience discrimination at work, cannot fit comfortably in theatre seats, or ride in a bus or plane.
• Increased surgical risks: Obese individuals are at high risk for surgical complications because they may be experiencing medical problems listed above.