American Medical Association Family Medical Guide - American Medical Association [45]
Type 2 Diabetes
More than 16 million Americans have type 2 diabetes, and about a third of them don’t know it because the disorder causes no symptoms in the early stages. Type 2 diabetes tends to run in families, but being overweight is a stronger risk factor than heredity. This means that even if you have a family history of diabetes, you can prevent it or delay it by keeping your weight within a healthy range and getting plenty of exercise. Long-term effects of diabetes include blindness, kidney disease, and poor circulation (which frequently results in amputation of lower limbs). People with diabetes also have an increased risk of heart disease, stroke, and high blood pressure.
Cancer
Being overweight appears to increase a person’s chances of developing some types of cancer, including cancer of the gallbladder, colon, prostate, uterus, kidney, ovary, and breast. Obesity has also been linked to cancers of the liver, pancreas, rectum, and esophagus. Doctors don’t know exactly how obesity increases the risk of cancer because the mechanisms vary for different types of cancer and because obesity results from a complex interaction of inherited and lifestyle factors, any of which could influence the risk of cancer.
For example, kidney cancer is more likely to develop in people who have high blood pressure, which is common in people who are obese. Obesity’s role in esophageal cancer appears to be the link between obesity and gastrointestinal reflux disease (GERD; see page 750), which causes inflammation in tissues in the esophagus; chronic inflammation can cause precancerous changes in cells. Some cancers, such as colon cancer, breast cancer, and prostate cancer, seem to result from the interaction of a combination of factors such as diet, weight, and physical activity.
If you have a family history of any type of cancer, especially in a relative who developed cancer before age 60, you should be especially diligent about maintaining a healthy weight. Your doctor also will recommend regular screening tests such as a colonoscopy (see page 767) for colon cancer and a mammogram (see page 141) for breast cancer, usually beginning at about age 40.
Joint Problems
Joint problems frequently develop in people who are overweight. Excess weight increases pressure on the joints in the knees, hips, and lower back, causing the cartilage (the tissue that cushions and protects the joints) to gradually wear away, leading to a type of arthritis called osteoarthritis (see page 996). Over time, the joint damage can become so severe and painful that the joint may have to be surgically replaced (see page 1000). Inflammation of the tendons (tendinitis; see page 984) is also common in overweight people. The tendons can become sore and inflamed from such routine activities as walking. Losing weight reduces wear and tear on joints and tendons and can often help relieve the pain of osteoarthritis.
Sleep Apnea
Sleep apnea (see page 636) is a potentially life-threatening condition that is closely linked to being overweight. The disorder can cause breathing to stop for brief periods of 20 seconds or more several times a night during sleep. Sleep apnea can lead to congestive heart failure (see page 570) because the condition forces the heart to work harder to supply oxygen to the tissues. Weight loss often diminishes or eliminates sleep apnea.
Gallbladder Disease
The risk of developing gallstones (small, hardened masses of cholesterol, calcium salts, and bile pigments) rises as a person’s weight increases. Although doctors don’t fully understand why this occurs, they think that being overweight causes the liver to produce more cholesterol than usual, and excess cholesterol can form gallstones. People who are overweight also may have an enlarged gallbladder that does not empty normally or completely, which increases their risk of developing gallstones. People who carry excess body fat around the abdomen seem