August 27, 2008
Type of Fat, More Than Weight, Indicates Risks
By MARJIE GILLIAM
There is no doubt about it, an expanding waistline is a key predictor of future health problems.
Visceral fat contributes to risk of heart disease, metabolic syndrome and type 2 diabetes and is being studied for its possible association to other medical conditions. Visceral fat accumulates around the midsection, in and around the internal organs and is metabolized by the liver, which turns it into blood cholesterol. Subcutaneous fat is less dangerous. This type of fat lies just under the skin and is easy to see, and typically accumulates on the hips, thighs, and arms, as well as around the waist.
We know that being overweight is associated with many diseases, but it is also true that thin to normal weight individuals can carry unhealthy levels of intraabdominal (visceral) fat. For example, a normal weight or thin person may never eat enough calories to become overweight, but may choose foods high in saturated fat, trans fats and/or unnecessary added sugars, causing visceral fat levels to increase. A person who over-consumes calories but makes healthy food choices and is active on a regular basis, even if overweight, can carry lower levels of visceral fat. In short, body composition (ratio of muscle to fat) and importantly, type of fat, is a much better predictor of health risk than scale weight.
One commonly used indicator of intra-abdominal fat is waist circumference. Increased risks for heart disease and diabetes is known to occur for women when waist circumference is more than 35 inches, and for men, 40 inches. Checking waist size is just one way to help determine health status, and is typically used for those who are overweight. Just as scale weight is only one way to help gauge health status, for thin to normal weight people, waist circumference may be under the number of inches considered unhealthy, but they may still have higher levels of dangerous visceral fat.
To measure waist circumference, use a soft, flexible tape measure, wrapping around your middle at the level of your belly button.
Tip: Just as your weight can fluctuate from day to day and hour to hour, waistline measurements can also differ, so for best comparisons, try to measure at the same time for each reading.
Hip-to-waist ratio is calculated by dividing your waist measurement by your hip measurement. Measuring both the hips and waist helps you to determine whether you are an apple shape, carrying a higher amount of body fat around the middle, or a pear shape, with fat deposited primarily around the hips. To measure your waist-to-hip ratio place the tape at the level of the top of the hipbones, record the number of inches, and then measure your waist at or just above the belly button. Then, divide your waist circumference by your hip circumference. Hip ratio should be below 0.8 for a woman and below 1.0 for a man.
In addition to heart disease and type 2 diabetes, evidence is mounting that visceral fat may also contribute to increased risk of stroke and some forms of cancer such as colon and breast cancer. Thankfully, visceral fat can be easily decreased with positive lifestyle changes. An exercise program equivalent to just 30 minutes six days a week can help prevent additional accumulation of visceral fat, and doing more than this can reverse the amount already present. Both resistance training and cardiovascular exercise are recommended in order to burn visceral fat most effectively. Studies have shown that even with moderate weight loss of 5 percent to 10 percent, visceral fat levels can be reduced 30 percent or more.
BMI calculation is an indicator of total body fat that is based on height and weight. In one study where participants were scanned to determine body fat levels, as many as 45 percent of women who had normal BMI (body mass index) scores had excessive levels of internal fat. Among men, the percentage was nearly 60 percent. While BMI can be a useful way to help assess health, it is limited. This is because weight is a factor in calculating BMI, and so, can overestimate body fat in muscular people and underestimate it in those who weigh less due to loss of muscle mass and bone density. Unfortunately, most body fat calculations are based on the assumption that the heavier the person is, the greater the body fat must be, but in reality, this is not always the case. As an example, taking twins who are equal weight and height, one a couch potato and the other an athlete, body composition (ratio of muscle to fat) differ significantly, as do health risks.
Next week: Is there a link between menopause and weight gain?
Marjie Gilliam is an International Sports Sciences Association Master certified personal trainer and fitness consultant. Contact her in care of the Dayton Daily News or at (937) 878-9018. Her Web site is at www.ohtrainer.com.
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