Your Scale May Be Lying to You

It’s not that your trusty bathroom scale is malicious…more along the lines of deceptive.  What do I mean by this?  Well, weight is defined as “the vertical force exerted by a mass as a result of gravity.”  So while your bathroom scale is accurate in terms of measuring the effects of gravity on you, it’s not telling you the whole story.  What it doesn’t tell you is exactly what mother earth is pulling on with her said gravitational force.  Enter the concept of body composition – the ratio of lean body mass to body fat.  To improve your overall health and performance, you want to work on increasing your lean body mass while simultaneously decreasing your body fat.  Your bathroom scale, however, could care less about this distinction.

Some of my clients struggle with this concept.  As their body starts to respond to changes we make to their nutrition and exercise plans their home scale initially doesn’t budge…but interestingly they notice that their clothes are fitting better.  Some of them protest when I prescribe an increase in both protein intake and strength training.  They quote the myth “But muscle weighs more than fat!”  My response?  While it may seem like semantics, the reality is that a pound of muscle and a pound of fat “weigh” the same on a scale, like a pound of feathers and a pound of rocks.  The skinny (pun intended) is the fact that fat takes up 3 to 4 times as much volume under the skin as muscle does.  Hmmm, weight vs. volume.  And you thought you would never use that grade school math again.  Building muscle while losing fat explains how people can see changes in their physique without much movement on the bathroom scale.

About two months ago a client of mine, who after a fair bit of humorous bargaining agreed to stop getting on her home scale twice a day, brought in an interesting article from the Wall Street Journal, which opens with the question “Can you be normal weight and fat at the same time?”  The short answer is yes.  The article is based on a report recently published by the Mayo Clinic, which coined a new phrase for this phenomenon: normal weight obesity.  The highlights of the report’s finding are as follows:


  • The amount of fat in your body can cause you and your heart problems even if you don't look overweight and if the scale tells you you're healthy.

  • The research suggests that body mass index, or BMI, the tool doctors and researchers often use to determine whether a person is obese, may fall short in some cases as an indicator of good health.  BMI is obtained by dividing your weight in kilograms by your height in meters squared, but makes no distinction between muscle vs. fat.  As one commenter on the WSJ article pointed out, according to BMI, Olympic sprinters are overweight and Hollywood drug-addicted starlets are fit.

  • High body fat among normal-weight men and women was associated with a nearly four-fold increase in the risk for metabolic syndrome—a cluster of abnormalities including elevated blood sugar and blood pressure.

  • Measuring body fat using methods such as a bioelectrical impedence scale (which I use in my office) or body calipers could help identify previously unappreciated risk in the normal-weight population.

  • One of the problems is that body composition measurement isn’t a widely accepted clinical measurement.  And there isn't a consensus among medical experts about what percentage of body fat is "normal" or what level indicates higher risk.  Click here to read the entire article.


Clearly more research is needed to determine the most cost effective and accurate way to measure body composition as well as a consensus on what those numbers should be for optimal health.  In the meantime, consider having your body composition measured, which will help point you towards necessary changes in your nutrition and exercise plans.  Then you can also answer the question that may be on your mind after reading this post: Is your scale lying to you?