Beyond the Bathroom Scale

These techniques can help accurately gauge your weight-loss success.


The bathroom scale may not be the most reliable means of determining how much weight you may need to lose, say experts. That’s because body weight doesn't take into account the proportion of fat in the body, or where that fat is deposited. Other measuring devices may deliver a more accurate assessment of body fat versus muscle mass, though they aren’t all easy to find.

Most experts agree that each method has its limitations, and sometimes the “mirror test” is the best one all.  


Body mass index (BMI) has largely replaced the number on the scale alone to determine overweight or obesity. Although it is relatively simple to calculate, it has its drawbacks.  For one, it does not identify fat content, saysRobert Davidson, PhD, the program director of the Nutrition and Human Performance Program at Logan University in St. Louis.

“A person could have a normal BMI but still need to lose weight,” says exercise physiologist, Lauren McDonald, at Duke Health & Fitness Center in Durham, N.C.  “It's one of the inaccuracies of BMI measurements. It depends on where the weight is being carried. Carrying excess weight in the abdomen is riskier to your health than excess weight around the hips and thighs. Bottom line: BMI is a good screening tool but not a diagnostic tool."   

Skin-fold Measurement

The skin-fold technique is commonly used to determine body fat percentage. It involves pinching your skin at specific locations, pulling the fold away from the underlying muscle, and using a skin-fold caliper to measure its thickness.  A formula is used to translate the skin fold thickness into a percentage of body fat.

While you can buy skin fold calipers for as little as $15, the ones used by professionals can run up to $500, and you will need a trained professional to take the measurement.

Although the technique is reliable if performed accurately, it is technically challenging to do accurately, says Davidson.

Underwater Hydrostatic Weighing

This method of determining the ratio of body fat to lean mass is based on the principle that muscle sinks and fat floats, so a leaner person will weigh more under water than someone with a lot of body fat.

For this method, you are weighed on dry land and then three additional times while sitting on a special scale in a tank of water. Your underwater weights are averaged and your lean-to-fat ratio is calculated.

The technique is considered the gold standard for determining body fat percentage, says Davidson. The drawback: It may be difficult to find a facility that performs it.

Dual-energy X-ray Absorptiometry (DXA)

The same X-ray technique used to measure bone density can also be used to accurately evaluate body composition and determine the amount of lean and fat tissue. The procedure is available at many hospitals and clinics and costs around $100.

Waist circumference

One of the simplest ways to know you are gaining weight is to feel your waist band getting tighter. Seeing the numbers increase when you measure your waist is another. “The simpler the better,” says Missouri State University professor and exercise physiologist Barbara Bushman, PhD.  Another benefit of measuring waist circumference is that it is a good indicator of cardiovascular risk.  Weight gain around the midsection is typically fat and abdominal fat is associated with increased risk of cardiovascular disease.

Bottom Line

“Some people are encouraged and motivated by numbers and measurements, while others get discouraged and fail to realize the progress that isn't reflected on a scale, chart or measuring tape. I encourage my clients to shy away from obsessing over the scale and continuous measuring, and have them focus on how they feel, how they look, how their clothes feel. If you increase activity, eat a balanced diet, over time, you will see results.”

Updated November 2015

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