Obesity

Obesity

Causes and Complications
Diagnosis
Treatment

Causes and Complications

Causes

Obesity is considered a complex and chronic disease with many causes. It is not simply a result of overeating. Research has shown that genetics often play a significant role in determining a person's body weight, particularly for morbidly obese people.

In addition to genetics, factors such as the environment, metabolism, eating disorders and certain medical conditions may contribute to obesity.

Genetics

Research has shown that a person's genes play an important role in their tendency to gain weight. Just as some genes determine eye color or height, others affect appetite, ability to feel full or satisfied, metabolism, fat-storing ability and even natural activity levels.

Environment

Environmental and genetic factors are closely intertwined. If you have a genetic predisposition towards obesity, the modern American lifestyle and environment may make controlling weight more difficult.

Fast food, long days sitting at a desk and suburban neighborhoods that require cars exacerbate hereditary factors such as metabolism and efficient fat storage. For those suffering from morbid obesity, anything less than a total change in environment usually results in failure to reach and maintain a healthy body weight.

Metabolism

We used to think that a person could lose weight if they burned more calories than they consumed. Now we know that for some people, it's not that simple.

Obesity researchers now refer to a theory called the "set point," a sort of thermostat in the brain that makes people resistant to either weight gain or loss. If you try to override the set point by drastically cutting your calorie intake, your brain responds by lowering metabolism and slowing activity. You then gain back any weight you lost.

Complications

Being obese significantly increases your chance of developing chronic, life-threatening diseases. These include:

• Depression -- Depression is very common after repeated failure with dieting and disapproval from family, friends and the public.

• Diabetes -- Obese individuals develop a resistance to insulin, which regulates blood sugar levels. Over time, high blood sugar can cause type 2 diabetes that can lead to serious damage to the body.

• Gastroesophageal Reflux or Heartburn -- When acid escapes from the stomach into the esophagus through a weak or overloaded valve, gastroesophageal reflux can occur, causing "heartburn" and acid indigestion. Gastroesophageal reflux disease can lead to Barrett's esophagus, a pre-cancerous change in the lining of the esophagus and a cause of esophageal cancer.

• High Blood Pressure and Heart Disease -- Excess body weight strains the heart. This may lead to high blood pressure, which can cause strokes as well as heart and kidney damage.

• Incontinence -- In obese people, a large, heavy abdomen may cause the valve on the urinary bladder to weaken, leading to urinary stress incontinence or the leakage of urine with coughing, sneezing or laughing.

• Infertility -- Obese women may experience infertility -- an inability or diminished ability to become pregnant.

• Menstrual Irregularities -- Morbidly obese women may experience disruptions of menstrual cycles as well as abnormal flow and increased pain.

• Osteoarthritis -- The weight placed on joints, particularly knees and hips, results in rapid wear and tear of joints as well as pain caused by inflammation, called osteoarthritis . Excess weight puts a strain on bones and muscles of the back, which can cause disk problems, pain and decreased mobility.

• Sleep Apnea and Respiratory Problems -- Fat deposits in the tongue and neck can cause intermittent obstruction of your air passage, called sleep apnea . Because the obstruction is more severe when sleeping on your back, you may wake frequently to reposition yourself. Loss of sleep often causes drowsiness and headaches.

Reviewed by health care specialists at UCSF Medical Center.
Last updated May 8, 2007