What Roles Do Body Fat Play in Health?

Gender affects how much body fat one has. Girls start out with 10 to 15 percent more body fat than boys. After puberty, the percentage increases; girls have 20 to 30 percent more body fat than boys. A boy's growth spurt is usually the result of an increase in muscle and lean tissue, while a girl's growth spurt is usually due to an increase in fat tissue. The extra fat is a normal part of sexual development.

Where a person carries his or her body fat can also make a difference. Fat in the abdominal area seems to be more dangerous than carrying extra fat in the thighs or hips. Health experts say that men with a waist that is more than 40 inches and women with a waist of 35 inches or more are at risk of serious health problems.

Another way to assess your health risk is to calculate the ratio of fat around your waist to the fat around your hips and thighs. Most people know how to measure their waist. If you aren't sure where to measure, try about two inches above your belly button. The next measurement should be around the widest part of your hips and thighs. It helps to stand In front of a mirror to be sure you're getting accurate measurements. Then divide the waist measurement by the hip/thigh measurement. Health risks are believed to occur among men with a ratio of 1.0 or more and women with a ratio of 0.8 or more.

Jules Hirsch and Rudolph Liebel, researchers at Rockefeller University, found that fat cells in the abdomen react differently to hormones in the body. They are especially interested in the fact that fat cells seem to be more resistant to insulin, a hormone that helps the body convert sugar into energy. As a result, the body produces more insulin. Their findings may explain the connection between abdominal fat and an increased risk of diabetes and heart disease. Since more men than women carry extra abdominal fat, their findings may also help explain why men are more prone to heart disease than women.

People who go on and off diets frequently have a tendency to put on more abdominal fat That's one reason to think twice before going on a fad diet.

Q & A

Question: Is there such thing as a "fat gene?"

Answer: Both human and animal studies have shown that genetics can play a role in being overweight or obese. At (east several dozen genes are involved in obesity, according to the American Dietetic Association (ADA). In 1994, scientists discovered a new hormone that is produced by fat cells and affects how the body regulates weight and feelings of fullness. The hormone is called ieptin. Those who are obese tend to have "an excess of circulating Ieptin in direct proportion to their body mass index," according to the ADA. People with anorexia typically have very low levels of leptin.