Those extra inches around the middle may signal increased fat around abdominal organs and rising health risks.
It’s a rare woman over age 50 who has the same waist measurement she had as a teenager. But in the past decade or so, women’s waistlines have been expanding regardless of age. A 2014 report from the National Health and Nutrition Examination Survey found that from 1999 to 2012, the average body mass index (BMI) for women age 20 or older held steady. But during the same period, the average female waistline grew slowly and steadily, from 36.2 inches to 37.8 inches. Researchers are still searching for an explanation for this phenomenon, but they do know one thing: increasing waistlines are linked to greater risks for heart disease, diabetes, and osteoporosis.
What’s in a waistline?
Regardless of whether your weight has changed over the years, your height is likely to have decreased, the result of declining volume in the intervertebral discs of the spine. As your torso shortens, your abdominal organs have less vertical space to inhabit, so they move horizontally. If you haven’t gained weight, an increase of an inch or two around the waist may simply reflect lost height.
However, if you’ve put on a few pounds and they’ve landed in your middle, the added waistline inches may reflect gains of subcutaneous fat (the “pinchable inch” or “spare tire” of fat just under the skin), visceral fat (padding around your internal organs), or both. While subcutaneous fat may be disconcerting, it’s visceral fat that poses health risks. “Visceral fat is definitely the worst,” says Dr. Miriam Bredella, associate professor of radiology at Harvard Medical School, who has studied the effects of fat distribution throughout the body.
Why location is important
How fat behaves varies according to its location. Subcutaneous fat, which typically builds up around the hips and thighs, basically serves as storage: it holds fatty acids in triglycerides — releasing them only when they are needed for energy. Research in the last few decades has determined that lower-body fat actually has a protective effect against diabetes and heart disease. Scientists speculate that it may help to lower the risk of those conditions by keeping fatty acids and inflammatory molecules out of circulation.
In contrast, visceral fat — which surrounds the liver, pancreas, and digestive organs — is very active. Fat cells in the abdomen are broken down rapidly and routinely, releasing fatty acids, hormones, and chemical messengers that act throughout the body.
What visceral fat does
As visceral fat increases, so does the risk of the following:
Cardiovascular disease. Visceral fat releases several molecules that play a role in triggering heart disease, including interleukin-6 and tumor necrosis factor, which are involved in inflammation; resistin, a hormone that contributes to insulin resistance; and plasminogen-activator inhibitor, which promotes blood clot formation.
Diabetes. Several factors related to visceral fat, including fat accumulation in the liver and increased levels of resistin, are involved in the development of diabetes.
Osteoporosis. Visceral fat is associated with an increased risk of bone loss because it inhibits the production of human growth hormone, which is important for bone health. The inflammatory molecules secreted by visceral fat also stimulate cells responsible for bone breakdown.
Identifying the danger zone
Studies have determined that for people with the same BMI but different waist sizes, the risk of heart disease is significantly higher for those with larger waistlines. Risk begins to increase when a woman’s waist measurement reaches 35 inches.
The waist-to-hip ratio also correlates closely with heart problems. People who tend to carry their weight in their hips and thighs (a “pear shape”) have lower waist-to-hip ratios and are less prone to heart disease than people with abdominal obesity (an “apple shape”). Women who have a waist-to-hip ratio greater than 0.9 are generally considered to have an apple shape.
Ways to minimize visceral fat
There is no sure way to target visceral fat. However, the following may help:
Curtail simple carbohydrates. Eating foods rich in simple carbohydrates — bread, potatoes, rice, pastries, and sugar-sweetened beverages — triggers your body to secrete more insulin, the hormone that regulates blood sugar. Insulin signals your body to store fat.
Exercise more. Sit-ups or other abdominal exercises may build muscle, but they won’t shrink your visceral fat. A combination of aerobic and strength training is best. Do at least 150 minutes a week of moderate-intensity exercise and strength training at least twice a week.
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