The scale is not the only way to determine success

For many people, trying to lose weight and get fit is just like looking at that confusing dashboard. Your doctor calculates your body mass index (BMI). Someone at the gym takes a skinfold measurement. And your bathroom scale awaits you each morning. Which one should you use to measure your progress?

"No tool is perfect, and each one tells you something different," says Marianne Dixie Stanforth, MS, a kinesiology lecturer at the University of Texas at Austin. "What's important in measuring fitness is body composition—how much fat versus how much muscle. Some tools, like a scale, won't tell you that." So what do measurement tools tell us?

The Scale
As we all know, a scale simply weighs the body. Weight fluctuates from day to day—even within the same day—and doesn't tell much about body composition. A very muscular 150-pound woman might look very different than a less muscular one. Ounce for ounce, muscle weighs more than fat (although it's denser and takes up less space), but a scale doesn't reflect that.

Tape Measurements
These are simple measurements at various places on the body. They chart a change in inches, but they can't tell if the tissue is muscle or fat. "A simple way to do girth (or tape) measurements is by trying on that merciless pair of jeans in the closet," says fitness consultant Neil Maki, MS. "You're probably losing fat and gaining muscle when they fit again."

Skinfold Measurements
For this method, measurements from folds of skin and fat at various sites on the body (for example: midriff, upper arm, back) are used to calculate body fat. It assumes, perhaps inaccurately, that fat under the skin is proportional to total body fat. But, says Maki, "This can be a good way to track your progress—to compare yourself to yourself. Make sure a skilled person is performing the test, and, as with all the techniques, keep all the variables consistent." That means try to have the same person give you the test each time, with the same equipment.

Body Mass Index
BMI gauges the relationship between your height and weight. "This number is more about measuring health risks from being overweight than about your daily or weekly fitness progress," says Stanforth. But it's a useful number to know, nonetheless. Knowing your health risks could give you the motivation you need to keep at being or getting fit. Find out your BMI with our BMI calculator.

Bioelectrical Impedance
Now available in home scales, this tool gauges body fat by how fast electrical stimulus travels through the body. It's based on the premise that lean muscle tissue conducts electricity faster than fat does. However, it doesn't work well for very lean or very obese people and is thrown off by dehydration and other bodily water fluctuations.

"The key is to find the method that works for you personally," says Stanforth. "For some of my clients, the scale only frustrates them. Girth measurements might be better, because then they can see how they're slimming down and toning up in a certain area. Find the method that motivates you, and go with it."