Though the term might sound dated, "middle-age spread”" is a greater concern than ever. As women go through their middle years, their proportion of fat to body weight tends to increase — more than it does in men. Especially at menopause, extra pounds tend to park themselves around the midsection, as the ratio of fat to lean tissue shifts and fat storage begins favoring the upper body over the hips and thighs. Even women who don't actually gain weight may still gain inches at the waist.
At one time, women might have accepted these changes as an inevitable fact of postmenopausal life. But we've now been put on notice that as our waistlines grow, so do our health risks. Abdominal, or visceral, fat is of particular concern because it's a key player in a variety of health problems — much more so than subcutaneous fat, the kind you can grasp with your hand. Visceral fat, on the other hand, lies out of reach, deep within the abdominal cavity, where it pads the spaces between our abdominal organs.
Visceral fat has been linked to metabolic disturbances and increased risk for cardiovascular disease and type 2 diabetes. In women, it is also associated with breast cancer and the need for gallbladder surgery.
Where’s the fat?
Fat accumulated in the lower body (the pear shape) is subcutaneous, while fat in the abdominal area (the apple shape) is largely visceral. Where a woman's fat ends up is influenced by several factors. Heredity is one: Scientists have identified a number of genes that help determine how many fat cells an individual develops and where these cells are stored (Proceedings of the National Academy of Sciences, April 25, 2006). Hormones are also involved. At menopause, estrogen production decreases and the ratio of androgen (male hormones present in small amounts in women) to estrogen increases — a shift that’s been linked in some studies to increased abdominal fat after menopause. Some researchers suspect that the drop in estrogen levels at menopause is also linked to increased levels of cortisol, a stress hormone that promotes the accumulation of abdominal fat.
As the evidence against abdominal fat mounts, researchers and clinicians are trying to measure it, correlate it with health risks, and monitor changes that occur with age and overall weight gain or loss. The most accurate measurement techniques, magnetic resonance imaging and computed tomography, are expensive and not available for routine use. However, research using these imaging methods has shown that waist circumference reflects abdominal fat. It has largely superseded waist-to-hip ratio (waist size divided by hip size) as an indicator of fat distribution, because it is easier to measure and about as accurate. There's also evidence that waist circumference is a better predictor of health problems than body mass index (BMI), which indicates only total body fat.
Measuring up
Researchers have tried several ways of measuring the links between health risks and body weight or fat distribution:
Body mass index (BMI). A ratio of weight in kilograms to the square of height in meters, BMI helps identify people whose weight increases their risk for several conditions, including heart disease, stroke, and diabetes. People with BMIs of 25–29.9 are considered overweight, and those with BMIs of 30 or over, obese. However, some researchers think BMI isn't always a valid indication of obesity, because it gives misleading results in people who are very muscular or very tall. To calculate your BMI, go to www.nhlbisupport.com/bmi or use this formula: Weight in pounds × 703 ÷ (height in inches)2.
Waist-to-hip ratio. To find your waist-to-hip ratio, divide your waist measurement at its narrowest point by your hip measurement at its widest point. As a marker of a person's abdominal fat, this measure outperforms BMI. For women, the risk for heart disease and stroke begins to rise at a ratio of about 0.8.
