Having too much body fat is associated with increased health issues. The location of that body fat might indicate what kind of health problems might be on your horizon. According to the American Heart Association, upper-body fat that accumulates at your waist indicates increased risks for high blood pressure, high cholesterol and diabetes. Lower-body fat, found around the hips and thighs, is associated with reduced memory according to a 2010 study published in the "Journal of the American Geriatric Society" by Northwestern University researcher Diana Kerwin.
Target Body Fat
The health risks of both upper- and lower-body fat come from having too much fat, but the body needs fat to function properly according to the University of New Mexico exercise scientists Len Kravitz and Vivian Heyward. Essential fat, which is needed for body functions, is found in bone marrow and the central nervous system as well as the heart, lungs, liver, spleen, kidneys, intestines and muscles. Kravitz and Heyward report that women have more essential body fat to help with child-bearing. Thus, the UNM scientists say that for optimal health, women should have body fat percentage between 18 and 30. Men should have a percentage of 10 to 25 percent.
Body Mass Index
According to the AHA, body mass index is an indirect way to measure total body composition. The National Center for Health Statistics says that having a BMI between 18.5 and 24.9 is ideal. Above 25 is considered overweight and a BMI over 30 is considered obese. BMI over 40 is a sign of extreme obesity.
Calculating BMI
The AHA says to calculate your BMI by multiplying how much you weigh in pounds by 703. Divide the answer by your height in inches and then divide that answer by your height in inches. If you are 5 feet 6 inches and weigh 150 lbs., for example, you would multiply 150 by 703 to get 105,450. Divide that by 66 for 1597.72, then divide that answer by 66 to find a BMI of 24.2.
Waist Circumference
BMI provides only half of the information needed to assess total body composition because fat location is important. Waist circumference, or the measurement around your natural waist, provides the other piece of information to assess your health risks. According to the AHA, men should have a waist circumference less than 40 inches and women should be less than 35 inches. Measurements above this, along with a BMI over 25, indicate upper-body fat and higher risks for health problems.
Regional Body Composition
Bioelectrical impendance is another way to measure body fat. This method uses electrodes to send a safe, low-voltage electrical current through the body. Fat is a poor conductor due to its lack of water, but the part of the body that is not fat conducts this current well because it is predominantly water. Body fat is then calculated based on how fast the current passes through the body. Devises such as hand-held analyzers and specialized scales make this form of body fat measurement available to the public. However, these devises only measure regional body fat -- upper or lower, but not the full body. This does not provide the full picture of body composition, according to a 2002 study published in the "North Dakota Academy of Science Proceedings." In order to understand health risks, you need to know total body composition as well as where your fat is located.
References
- University of New Mexico: Getting a Grip on Body Composition
- American Heart Association: Body Composition Tests
- "Diabetes"; Leptin Secretion From Subcutaneous and Visceral Adipose Tissue in Women; Harmelen et al; 1998
- "North Dakota Academy of Science Proceedings"; Regional and Whole Body Composition and Bioelectrical Impedance Analysis; Siders et al; 2002
- "Journal of American Geriatrics Society"; The Cross-Sectional Relationship Between Body Mass Index, Waist--Hip Ratio, and Cognitive Performance in Postmenopausal Women Enrolled in the Women's Health Initiative; Kerwin et al; 2010
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