A: This is a trick question — both are useful measures! When it comes to assessing health, I like to use a trio of measurements: weight, body fat and waist circumference.
Body weight is measured by using a scale. You can use body weight to calculate your Body Mass Index (use the BMI calculator on LifetimeTV.com's diet & nutrition page by clicking here), which can determine your risk of health problems such as diabetes, heart disease and cancer. The goal is to have a BMI of 18.5 to 25 — this translates to a lower risk of disease. Having said that, it's important to note that BMI is not a good measurement system for certain people, such as athletes (they tend to weigh more, but the extra weight is healthy muscle tissue) and the elderly (they will weigh less but have more body fat).
Body-fat testing can go a step further than weight and BMI because it can tell us our fat-to-muscle ratio. Too much body fat can lead to increased risk of chronic disease. The healthy range of body fat for women age 18 to 39 is 21 to 33 percent, and for women age 40 to 59 it's 23 to 34 percent. Your body fat can be measured in several ways, each of which has pros and cons. These include the following:
• DEXA scan (Dual Energy X-Ray Absorptiometry) is a test typically performed at a hospital, although some gyms may also offer it. This method uses X-rays to measure how much fat, muscle and bone you have. It is one of the most accurate ways to determine body fat, but it can be difficult to find a place to get it done and may cost several hundred dollars.
• Underwater weighing is typically done at a university or gym. This method requires that you be lowered into a tank of water. Your body fat is measured based on how much water you displace. It is one of the most accurate ways to assess body fat, but, as with the DEXA scan, it can be difficult to find a location and may be pricey.
• The caliper method is done at a gym or by a health-care provider who will pinch and measure the fat on three to seven different locations around your body. Those measurements are plugged into a mathematical equation to estimate your body fat. Getting a caliper test is typically inexpensive, but the measurements are accurate only if the tester knows the proper technique.
• Bioelectrical impedance analysis (BIA) sends a low electrical signal through your body to estimate body fat (the fatter you are, the slower the currents travel). BIA comes in home-scale versions, which are only fairly accurate. If you use one of these scales, it's very important to follow the directions that come with it (like waiting at least three hours after eating or drinking anything) to get the most accurate results.
Finally, another very important indictor of health is your waist circumference. Measuring your waist (the circumference should be less than 35 inches for women) will give you an indication of how much "visceral" fat you have. Visceral fat is the type that's found deep inside your abdomen and around your organs. Having excess midsection fat causes organs such as the liver and pancreas to malfunction, and can therefore put you at risk for developing chronic illnesses like diabetes and heart disease.
Use all three measures to get a good picture of your health. If your BMI, body fat and/or waist measurement are high, you can take control by getting regular cardiovascular exercise (at least 30 minutes five times per week), adding strength training to your workout routine (at least twice a week), and eating a low-calorie, balanced diet (try cutting out 500 calories from what you currently eat and you should lose about a pound per week). And remember to visit your doctor for regular physicals and blood tests to check things such as cholesterol, glucose and blood pressure.
Dawn Jackson Blatner is a registered and licensed dietitian, and a national media spokesperson for the American Dietetic Association. Read more about her here.
