Research Review
Home scales can accurately measure body fat
To help stay on track with a weight-loss program, weigh yourself weekly (a new scale released in the market with a feature to measure body fat) and record the progress The scale instructions give the normal values for body-fat percentages, but some people are not sure if they should pay more attention to the body fat or to the weight itself.
Can a scale really measure body fat? Most of us think that skin-fold calipers are more effective. Well, according to Julie L Mitchell, MD, MS, Assistant Professor of Medicine at the Medical College of Wisconsin, obesity is a body mass index of greater than 30. Many body mass calculators are available online.
The scale measures body-fat percentage with a technique called "bioelectrical Impedance." A weak electric current is sent from the scale, up one foot, through the body and back to the scale down the other foot. The speed at which the current travels are dependent on the relative amount of the more conductive lean tissue compared with the less conductive fat. Similarly, hand-held devices send current from one thumb through the body to the other thumb. This method is about 95% to 97% accurate, a bit better measure than the skin-fold calipers.
Of course, it may not be as simple as a BMI alone, because both weight-lifters and sedentary folks will be heavier than exercisers, and it is the extra fat on the body (and extra food that is not burned up with exercise) that contributes to the serious problems.
If you are doing a lot of weight training while reducing your food intake in your weight-loss program, your weight may not initially drop because as your fat converts to muscle, you become denser. In this case, you may wish to record your body-fat percentage along with your weight to get a better picture of your progress.
But for most obese people, the body weight tells the story, revealing the risk for problems such as heart disease. Obesity leads to high blood pressure, diabetes, coronary heart disease, arthritis, heartburn and sleep trouble, just to name a few. The clinical research that concluded that obesity led to these problems is based on the fact that obesity is defined as too much weight for your height.
Mitchell discusses a recent research which focused on the location of excess fat, not just how much. Apple-shaped bodies (where fat is deposited primarily around the middle) suffer more complications of obesity than pear-shaped bodies (where fat is deposited primarily in the buttocks and lower extremities). Here the best measure is the waist circumference or the waist-to-hip ratio. Normal waist circumference is less than 35 inches in women and 40 inches in men; normal waist-to-hip ratio is less than 0.9 in women and less than 1.0 in men.
Julie L Mitchell, MD, MS, Assistant Professor of Medicine at the Medical College of Wisconsin, practices at the Froedtert & The Medical College of Wisconsin General Internal Medicine Clinic - East. Her column appears in the Milwaukee Journal-Sentinel, JS On-Line.
References
Julie L Mitchell. Milwaukee Journal-Sentinel, JS On-Line http://www.jsonline.com/
MCW HealthLink , http://healthlink.mcw.edu/article/1031002657.html
Monika
Monika Bhatia
Project Manager and Editor, Quality4life
4 August 2006
