Why Your Scale Can't Be Trusted

by Jade Teta

We talk a lot about the need to stop playing the weight loss game here at Metabolic Effect.  This is a game where the scale is used daily to judge the progress of a diet and exercise program. Measuring your weight alone tells you NOTHING about the quality of the weight you are losing.
How do you know if you are losing fat, water or worse muscle? If you are using just a scale you have no idea. Losing or gaining 5 pounds of fat over a weekend is physiologically impossible, but the scale has convinced many that it can happen. A significant portion of those playing the weight loss game believe the weight they lose or gain on a day to day basis is fat. And the popular media and weight loss experts do nothing to help them understand that not only is this not true, but it also is one of the major reasons they continue to suffer from yo-yo weight regain and can’t lose fat as they age.

Losing Muscle
I want to introduce you to my wife, Jill Coleman and my sister-in-law ,Dr Jillian Sarno Teta. They are both named Jillian, but we call my Jillian Jill and Keoni’s Jillian Jillian. Both are from Boston and are the same age distance from myself and Keoni. They are both past track athletes. And both are ridiculously fit women who lift weights, are professional physique competitors and fitness models. They are both wicked smaaaht (a reference to their Boston roots) and are Metabolic Effect team members. They play a key role in developing the ME lifestyle programs and systems.
I bring our two favorite women in the world up because these women have muscle and weigh more than anybody could guess.  A running joke in our family is to take them to the carnival or fair and find that guy that guesses weight. We always go home with an extra stuffed animal, because they always guess 10 to 20 pounds lighter.  Jill weighs 150 to 160 but they always guess in the 130s.  Jillian weighs in the 130-140s and they always guess in the 10 to 20 pounds lighter.  In other words, these two fit women look twenty pounds lighter than what they actually are because they have maintained their muscle. Their bodies are tight, toned and look much tinier than the scale might suggest.

I bring this up because one of the single most important mind-shifts to break is how much you weigh. Because if you are losing weight indiscriminately and shedding muscle instead of fat (which almost all dieters are), your metabolism is going to be in BIG trouble over the long run.
Muscle is absolutely essential for maintaining basal metabolic rate. Basal metabolic rate (BMR) accounts for over two thirds of the calories burned at rest and more than half of BMR can be accounted for by the amount muscle a person has (1). It was shown as far back as 1988 in the February issue of the New England Journal of medicine that a slowed BMR is a predictor of fat gain over the course of a 2-year period (2). In this study those with the slowest metabolic rate had a 4-fold increase in gaining 15 or more pounds over the next 2 years. This explains why 66% of individuals going on weight loss diets end up fatter 2 years later compared to when they started the diet (3)
So, lose muscle and you lose your metabolic potential!! And guess what is a great formula for losing muscle? The “eat less, exercise more” model. A low calorie diet combined with aerobic exercise is a solution that may make you smaller  for a short period of time, but will end up making you either flabbier or fatter in the long run and in a terrible position to make losing weight again that much more difficult, because you lost muscle along the way.

A study published in the Journal of the American College of Nutrition in April 1999 showed just how damaging the standard weight loss model can be on metabolic efficiency (4).  This study looked at a group of obese individuals who were put on a very low calorie diet and assigned to one of two exercise regimes. One group followed the popular aerobic exercise model (walking, biking, or jogging four times per week), while the second group did resistance training three times per week and no aerobic exercise.

At the end of the twelve-week study, both groups lost weight but the difference in muscle vs. fat loss was striking.  The aerobic group lost 37 pounds over the course of the study.  The resistance-training group lost 32 pounds. Of the 37 pounds lost by the aerobic group, 10 pounds of muscle was lost on average. In comparison, the resistance-training group lost fat exclusively and had no muscle loss. This had consequences on basal metabolic rate (BMR). At the conclusion of the study, the aerobic group was shown to be burning 210 fewer calories at rest per day while the resistance-training group actually increased their metabolism by 63 calories per day. No wonder yo-yo weight regain is such an issue.

Measure Fat Loss
So, hopefully you understand the futility of putting too much stock in the weight showing on your scale.  If the scale is going down, you better make sure you are losing fat, NOT muscle. If you are losing muscle you should brace yourself for the weight gain rebound that is sure to come, as well as a less efficient metabolism later.  This chronic dieting mindset and attachment to the scale may ironically be the very thing that has caused your metabolism to now be unresponsive to your attempts at body change.  The weight loss game is rigged against you, so please stop playing it.
To make sure you are losing fat and not muscle you need to measure fat loss. There are several good ways to do this in a lab setting (DEXA, Hydrostatic weighing, Air Displacment Plethysmography, etc). These get you as close to accurate body fat measures as possible. The problem is these methods are expensive, and not widely available.  If you are going to track fat loss you need something that is cheap, convenient and able to show you a general trend of fat loss versus water or muscle loss. Here are our favorite methods below.

1) Bio-electrical impedance: These machines can be held or stood on (you need bare feet and the standing modules are better than the handheld in our opinion). They push an electrical current into the body (you can’t feel it) and the machines measures the “impedance” or resistance to that current.  Water is a good conductor of electricity and fat is not.  Where is most of the water in the body? The Muscle.

So, this machine makes a best guess of how much muscle, versus water, versus fat you have based on the impedance value along with height and weight.  It takes these numbers and plugs them into regression equations based off of thousands of DEXA scan studies and generates a estimate of your actual body fat.

It is important to understand this is a hydration measuring device NOT a fat measuring device (meaning it does not measure fat directly but estimates it based on hydration) and because water fluctuates so greatly in the body (the reason you can gain or lose 5 pounds in a weekend) you have to know how to read them.  They are NOT accurate, but when used consistently at the same time, under the same conditions weekly they definitely show a trend of muscle loss or fat loss.

A couple hints with these machines about the way we use them

- Measure only 1 time per week

- Measure first thing Friday morning before eating or drinking anything.
subtract the water value from the muscle mass value (BTW muscle mass, also reported as fat free mass, is not really a measure for muscle but rather a measure for water, organ tissue, bone and muscle.  Organ and bone will not change significantly, so you are left with water and muscle. subtracting the water value from the fat free mass value will give you an indication of muscle gain or loss)

- Consider measures taken during menses as comparable to only other measures done during menses.
The first week of a low carb diet will artificially look as if you gained a significant amount of fat. This is because insulin makes you hold onto both sodium and glycogen.  When you go low carb, you will lower insulin quickly and lose glycogen and sodium and shed a significant amount of weight (it is all water). But since this water goes into the calculation for fat free mass or muscle mass it will artificially look as if you lost muscle and your body fat % will be reported on the machine as going up. In fact it did not. This is an artifact and will correct.  BTW, this is a good sign and an indication you are entering “fat burning mode”

- We use the Tanita Ironman Series and recommend unit BC 549
Optimal for women is between than 25%-15% body fat (my opinion)
Optimal for men is between 15% and 8% body fat (my opinion)

2) Weight and circumference: This is not a great method either, but it can be useful.  This looks at weight along with circumference measures.  If you sign-up for our newsletter (top of the page to the right) one of the first things we give you is the sheet we use for those who are not going to invest in a body composition monitor like the ones above. As you can imagine if you lose muscle, your measurements on a tape measure will still go down. You can lose muscle and still fit in your skinny jeans.  So, these are less than perfect ways to judge fat loss. But, this is definitely better than weight alone.

Here are some pointers:
- Women losing fat will usually see the waist and bust size drop.  The hips may not change as much because it is a heavily muscled area
- Men will notice waist size decrease significantly.
- Measure one time per week under the same conditions using a tape measure allows you to track specific areas.
- Firmness and tone of the body is a good indicator.  If you are losing weight and getting flabby you are likely losing muscle.  If you are losing weight and getting tighter, you are probably losing fat.

Skin Caliper Testing: If you work with a trainer this is our favorite method.  The issue is that this takes a skilled practitioner to do and the same person must do it on you every time for accuracy. It is still the most accurate of the three methods listed here and the most repeatable in my opinion.  IF you can get skin calipers done we recommend you do.