How common is obesity?

Obesity has reached epidemic proportions in the United States. One in three Americans is obese. Obesity is also increasing rapidly throughout the world, and the incidence of obesity has nearly doubled form 1991 to 1998.

What are the health risks associated with obesity?

Obesity is not just a cosmetic consideration; it is a dire health dilemma directly harmful to one’s health. In the United States, roughly 300,000 deaths per year are directly related to obesity, and more than 80% of these deaths are in patients with a BMI (body mass index, which will be discussed later in this article) over 30. Obesity also increases the risk of developing a number of chronic diseases including:

 
• Insulin Resistance. Insulin is necessary for the transport of blood glucose (sugar) into the cells of muscle and fat (which is then used for energy). By transporting glucose into cells, insulin keeps the blood glucose levels in the normal range. Insulin resistance (IR) is the condition whereby the effectiveness of insulin in transporting glucose (sugar) into cells is diminished. Fat cells are more insulin resistant than muscle cells; therefore, one important cause of IR is obesity. The pancreas initially responds to IR by producing more insulin. As long as the pancreas can produce enough insulin to overcome this resistance, blood glucose levels remain normal. This IR state (characterized by normal blood glucose levels and high insulin levels) can last years. Once the pancreas can no longer keep up with producing high levels of insulin, blood glucose levels begin to rise, resulting in type 2 diabetes, thus IR is a pre-diabetes condition. In fact scientists now believe that the atherosclerosis (hardening of the arteries) associated with diabetes likely develops during this IR period.  
• Type 2 (adult-onset) diabetes. The risk of type 2 diabetes increases with the degree and duration of obesity. Type 2 diabetes is associated with central obesity; a person with central obesity has excess fat around his/her waist, so that the body is shaped like an apple.  
• High blood pressure (hypertension). Hypertension is common among obese adults. A Norwegian study showed that weight gain tended to increase blood pressure in women more significantly than in men. The risk of developing high blood pressure is also higher in obese people who are apple shaped (central obesity) than in people who are pear shaped (fat distribution mainly in hips and thighs).  
• High cholesterol (hypercholesterolemia)  
• Stroke (cerebrovascular accident or CVA)  
• Heart attack. The Nurses Health Study found that the risk of developing coronary artery disease increased 3 to 4 times in women who had a BMI greater than 29. A Finnish study showed that for every one kilogram (2.2 pounds) increase in body weight, the risk of death from coronary artery disease increased by one percent. In patients who have already had a heart attack, obesity is associated with an increased likelihood of a second heart attack.  
• Congestive heart failure  
• Cancer. While not conclusively proven, some observational studies have linked obesity to cancer of the colon in men and women, cancer of the rectum and prostate in men, and cancer of the gallbladder and uterus in women. Obesity may also be associated with breast cancer, particularly in postmenopausal women. Fat tissue is important in the production of estrogen, and prolonged exposure to high levels of estrogen increases the risk of breast cancer.  
• Gallstones  
• Gout and gouty arthritis  
• Osteoarthritis (degenerative arthritis) of the knees, hips, and the lower back  
• Sleep apnea  
• Pickwickian syndrome (obesity, red face, underventilation, and drowsiness)

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Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30329-4027, USA