The number on the scale isn't the be-all, end-all in measuring your fitness or health. Your body composition, or the ratio of your lean tissue to adipose tissue, is usually a better indicator of how your muscle-building or weight-loss efforts are going. Although it won't give you a perfect read on your body composition, measuring the circumference of certain sites on your body, including your thighs, is an inexpensive, easy-to-perform way of tracking your progress over time.
Measuring Thigh Circumference
It's always easier to take body circumference measurements with the help of a friend or trainer, if only because this lets you stand upright in a relaxed position - something that's impossible to do when you're wrapping a measuring tape around your own thigh. With that said, as long as you're faithfully consistent in the way you take your measurements, they'll still give you a way of tracking how your body changes over time.
Step 1: Mark the Measuring Site
Stand upright, with your weight on both feet and thighs slightly apart. Have your friend or helper mark the midpoint between the top of your femur (the big bone in your thigh) and the top of your tibia or, more simply, the midpoint of your knee, underneath the kneecap. If you're really being precise, the mark should go on the outside of your right leg.
Measurements are most accurate when taken over bare skin - but not everybody is comfortable standing around in short-shorts or their underwear while someone else wraps a measuring tape around their thighs. If you want to keep your pants on for this measurement, wear form-fitting pants or tights (but not compression tights), and make it a point to wear the same pants or tights every time the measurement is taken. Otherwise, you might be measuring the change in your clothing's bulk instead of the changes in the size of your thigh.
Step 2: Measure Circumference
Have your helper wrap a flexible measuring tape around your thigh at the marked point. Make sure the tape is level - or to put it another way, horizontal - and flush against the skin, but not compressing it. Read the measurement where the "zero" mark on the tape intersects the rest of the measuring tape.
Step 3: Log Your Measurements
Be sure to note your thigh measurement in a notebook or mobile device. A single stand-alone measurement is really of no use to you, but if you measure your thighs every month, seeing the change in measurements over time will give you a good read on your progress.
Other Ways to Measure Body Composition
Methods like dual X-ray energy absorptiometry and hydrostatic weighing are the gold standard for measuring body composition, but they're expensive and usually only available in medical facilities, exercise science laboratories and some higher-end gyms.
Skinfold caliper measurements are an inexpensive means of tracking body composition, and when done by a skilled trainer, they can be very accurate. But they're also notoriously inconsistent when done by someone without the proper training, or even by two different people who are properly trained in doing them. So if you're using skinfold measurements to track your body composition, it's best to use them to track your relative progress - as opposed to hard, objective numbers - and to have the same person take the measurements each time.
About the Author
Lisa is a retired personal trainer with more than 4,000 hours of hands-on experience working with a variety of clients, from sports teams to weight loss and post-rehab populations. She's also a professional writer. Published credits in the health field include Livestrong.com, Feel Rich, SheKnows, Precor.com, and the East Coast magazine Breathe.