By Nanci Hellmich
Gannett News Service
Doctors should measure more than your weight at appointments. They should measure your waist.
For years, scientists have observed that an apple-shaped figure or a big beer belly is a health risk. But now they have gained more insight into why this is so.
They have discovered that people with wide girths are more likely to have large
amounts of deep-hidden belly fat around their organs. It might be the most dangerous kind of fat and could increase a person's risk of diabetes, heart disease, stroke and some types of cancer.
This fat, which is called visceral or intra-abdominal fat, is linked to high cholesterol, high insulin, high triglycerides, high blood pressure and other problems. Researchers are investigating whether visceral fat secretes more inflammatory molecules that are linked to diseases than other types of fat.
Get out the measuring tape
And because most people in the United States weigh too much and many carry extra weight in the belly, experts are racing to discover how to reduce the killer fat. So far, physical activity and weight loss appear to be the key. Several new studies indicate that regular exercise, such as brisk walking for 30 to 45 minutes a day, can significantly decrease such fat.
At greatest risk of developing health problems from too much hidden belly fat are men whose waists are wider than 40 inches and women whose waists are wider than 35 inches. If your waist measurement is that high, "you've fallen off the edge of the cliff," says George Blackburn, associate director of the division of nutrition at Harvard Medical School.
People with waists that wide need to reduce them immediately, says Robert Ross, an exercise physiologist at Queen's University in Kingston, Ontario. But even people whose waists are several inches smaller could be at risk, he says.
Experts say they don't know the optimal waist size for good health. But they do know this: Your waist circumference "is an absolute vital sign" in determining your health, Blackburn says. You need to know this plus your weight and body mass index, a formula that takes height and weight into account.
"In addition to the stethoscope around their necks, physicians should be carrying a tape measure," Ross says. Waist circumference is a risk factor for serious diseases, similar to factors such as weighing too much and high blood pressure, he says.
Most people don't know how much hidden belly fat they have because the only accurate way to determine it is with CT or MRI scans. But doing those tests for millions of people is unnecessary and too costly at this point, experts say. And measuring waist girth is a good guide.
Although people who are overweight or obese are more likely to have large
amounts of visceral fat, normal-weight people also can have too much.
Older people need to be particularly vigilant about their waist measurement. A recent study found that some men and women 70 to 80 years old with normal body weight still had an increased risk of type 2 diabetes if they had large amounts of visceral fat.
Scientists aren't sure why some people have more of this fat than others. As people get older, they often become less active, which could partly explain the increase in the fat, Ross says. Also, "it's very likely that genes, sex hormones and stress hormones (cortisol) play a role."
Scientists also don't know exactly why the visceral fat seems to take such a toll on health, and they are investigating it vigorously.
One explanation called the portal theory suggests that this fat secretes fatty acids near the liver, possibly causing some of the health problems that lead to diabetes, heart disease and high blood pressure. This theory is being questioned now, Ross says, and "there are far more new and exciting hypotheses currently being investigated."
Overall, visceral fat is a small amount of the total body fat. In a slightly overweight middle-aged man, about 15 percent to 20 percent of his fat is visceral fat, and about 10 percent to 15 percent of a pre-menopausal woman's body fat may be the intra-abdominal kind, he says.
Although visceral fat seems to be particularly hazardous to health, it's not the only bad guy under the tape measure. Subcutaneous fat, the kind right under the skin, also is a factor, Ross says. "Subcutaneous fat is not just hanging out. Both visceral and subcutaneous fat contribute to health problems, but it would appear that visceral contributes more."
The two fats act differently in the body, experts say. "If you put visceral fat in a petri dish and you put subcutaneous fat in a petri dish and stimulate them, the visceral fat will produce a lot more inflammatory molecules that can raise a person's risk of heart disease and diabetes," says Tim Church, medical director of the Cooper Institute in Dallas.
Weight loss, exercise key
Losing weight and increasing exercise appear to be key to decreasing this fat. A study at the Fred Hutchinson Cancer Center in Seattle found that overweight postmenopausal women who exercised regularly for a year lost 3.4 percent to 6.9 percent of their intra-abdominal fat, depending on how active they were. They were told not to change their diet. Exercisers lost about 3 pounds.
To get the benefit from physical activity, lead researcher Anne McTiernan recommends aiming for 30 to 45 minutes of brisk walking (as if you're late for the bus) five days a week. "I suspect if you exercise for 60 minutes a day, you'll get even more fat loss," she says.
The exercise should be intense enough that you feel your heart rate increase and you might sweat, but you should be able to hold a conversation.
Research by Ross of Queen's University showed that men who became more active lost a significant amount of this fat and reduced their waist size. These studies might help explain why some people who begin exercise programs say their pants fit better, but they're not noticing much weight loss, Church says.
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