9 Ways to Measure Fat & Body Composition | Best & Worst

If you want to lose weight you want and need ways to measure fat and body composition. Not tracking, tracking too little, or unnecessary information can lead you down a path where you might lose muscle, and ultimately regain more weight because of it. So this episode of Flipping 50 lays out many methods either believed or used to measure fat. 

This is the good, bad, and between. You may find an additional tool you want to use, and you will find some resources to make it easy to do. You may find you want an upgrade to what you’re doing now. 

Let’s dive into the 9 ways to measure fat and body composition I’ve included here. 


4 Ways to Measure Fat: Most Common

Traditional Scale 


Tells you your weight

Pros – the convenience of at-home, affordable, tells change even if not calibrated 

Cons – doesn’t measure body composition – your muscle and fat, calibration can be wrong

Girth Measurements


Typically taken at calf, thigh, hip, waist, chest, shoulder, triceps

Pros – convenient, affordable, combined with weight-only scales gives insight into the composition

Cons – inaccuracies can occur from pre to post, subjective errors pulling tighter/loser hold, placement variations

Body Mass Index (BMI)


Using your height and weight, a BMI rating places you in the ‘ideal of 19-24 or too low or too high.

Pros – simplistic requires no tools to do – online BMI calculators easily accessible 

Cons – zero indication of body composition, there are outliers – frail older adults/thick-framed muscular but shorter in height will never have “healthy BMI” ranges, not a good indication of overall health

My BMI currently is 22.3 while I’m at the lowest body fat I’ve been. At a lower weight, yet higher percent body fat my BMI is 21.6, falsely giving the impression I was healthier with those numbers. (The calculator is below for you to try. If you’ve lost weight). This measure alone could have you chasing the wrong goal line. 

Waist-to-Hip Ratio


Measures your waist and hip each at the smallest point. As it says, this is a measure of your proportions. You divide your waist measurement by the hip measure. Poor scores are indicative of a greater risk for heart disease. (.8 or lower is desirable for women and above .85 is classified as abdominal obesity by the World Health Organization).

Pros – convenient to measure, easy to calculate, tells you not just how much fat but where you carry it 

Cons – there’s room for error with the tape measure placement (parallel to the floor, at the right spot, and at the right spot pre and posttest).

Tip: in labs for nearly 18 years, here’s how we did this. When you measure, take the first measures. Then repeat for a total of 3 times. Take the average of your measure to record. 

3 Ways to Measure Fat & Body Composition that Require Equipment

Underwater Weighing 


Called hydrostatic weight, this was known as the gold standard or one of the most accurate ways to measure body fat until newer more advanced ways were developed. I’ve been in that deep tub numerous times and have tested hundreds if not thousands of students, faculty, and staff this way. 

The number of times I’ve shouted, “blow it out, blow it out” to a submerged student.. and lost my voice doing it… brings back memories! 

It was never foolproof. You and I don’t like to have any air in our lungs underwater. So, it’s very difficult to get a true measure. With antiquated scales, the needle was bouncing on the scale and you’re trying to read it while someone is wanting desperately to take a breath. 

If you ever have a chance to do this, take a pass. It’s based on Archimede’s principle. The amount of liquid a submerged object displaces is equivalent to the volume of the object. We take a measure on land, underwater and we measured with an elaborate calculation, your body density. From that, we calculated body fat. The heavier you are underwater (relatively), the lower your body fat. 

Pros – It’s safe, can be used if you have a pacemaker. Can be more accurate than many available methods of measuring 

Cons – it’s never going to be accurate if you can’t get the air out of your lungs (you’ll measure more fat than you are) 

The range of error was always about 2-3% plus or minus. 

Skinfold calipers


This is known as the “pinch test.” In labs, we’d do this one most commonly. I’ve pinched thousands of skinfolds in my career, and yet few in the last 10 years since I left the university. I no longer teach students to use them, pre and post-test students each semester, or work in the exercise clinic at the university. We also, however, did them selectively for people in fitness centers. If you’re of a certain size we’re simply not going to get an accurate reading. And often if your skin is too taught due to weight and inability to separate fat and muscle when attempting to get a skinfold, your posttest may be bigger than your pre simply because it then becomes easier to get a reading. 

Pros – relatively accessible in fitness centers, university settings

Cons – it all depends on your administrator’s skill level. It takes about 5000 practices to be an expert in anything. If you have a new trainer testing you, chances are accuracy is lower than the 3-4 percent accuracy possible. 

Dexascan (or MRI, CT scan)


When you get that bone density test, your technician can tell you various tissues including not only bone but muscle and fat. So be sure to ask if you’ve recently had a bone scan, you’ve also had one of the most accurate ways to measure your body fat).

Pros – non-invasive, accurate measure existing, you may already have or be in need of a bone scan 

Cons- expensive, not something used for the public for body composition testing 

Newer & Accessible Ways to Measure Fat & Benchmark

Bioelectrical Impedance (handheld)


Based on the fact fat is a poor conductor of electricity, and water is a conduit, you store water in muscle, hydration is important to the accuracy of your reading. Handheld tools used in fitness centers are probably less accurate than many methods of testing. That said, there’s more to consider.

Pros – easy, non-invasive (no dunk tank and no bruises from skinfolds)

Cons – accuracy is based on hydration, and handheld are less likely to  be as sensitive, error messages are common for large-sized individuals

Smart Scale 


Pros – affordable, convenient, non-invasive, ability to measure and show change over time

Cons – dependent on hydration (still bio-electrical impedance), accuracy is lower than other methods 

Why are these ways to measure fat so important and beneficial?

Measure Fat to Optimize Habits that Influence Body Composition

Your measures all tell you the sum of your daily habits. You know when you measure not if, but how they’re working. You know something isn’t working. You may not know exactly what but you have a measure so that you can look at whether you are: 

Eating enough High-quality protein 

Exercising to keep and gain lean muscle and avoid losing it

Sleeping enough 

Not allowing catabolic hormones or lack of anabolic to sabotage you

For help with all of those, if you have 20 or more pounds to lose, check here. I’ve gathered all the science of fitness and fitness nutrition after menopause for you. 



BMI calculator      

Waist-to-Hip Ratio tool    

WHO’S Waist Circumference and Waist-Hip Ratio paper  



Debra’s Top 3 Smart Scales (one for every budget)

Join the Flipping 50 Insiders group


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Learn how to measure!

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Circumference outside of both arms, at the armpit

Right Triceps
Halfway btwn shoulder & elbow, arm extended.

Find the widest point of girth at the hips

Right Thigh
Standing with weight on both legs, measure halfway between knee cap and hip flexor

Right Calf
Standing with weight on both legs, find the largest point of calf.

how to measure woman outline

Measure from the rib cage just under breasts at bra line

At the belly button/umbilicus

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