While the scale will tell you how much you weigh, it doesn’t tell you what your body is made of.
Body composition refers to everything in your body, split up into different compartments. Two compartments are commonly used: fat mass and fat-free mass.
Fat mass refers to all the fat tissue in your body. Fat-free mass is everything else, including muscle, organs, bone and fluid.
If both change at once, you might not see any changes in body weight.
For example, if you start exercising, you may gain two pounds of muscle in the first month. At the same time, you may lose two pounds of fat due to burning more calories through exercise or changes in your diet.
Since your fat-free mass increased by the same amount as your fat mass decreased, your body weight won’t change.
If you focus on the number on the scale, you may become discouraged or frustrated because your program “isn’t working.”
This is one example of why knowing your body composition is much more useful than knowing your body weight.
How Can You Assess It?
There are many methods to assess your body composition. Some are very simple and easy to use, while others are advanced and complicated.
The most accurate methods are usually expensive and only used in research or medical centers.
However, there are some simple methods you can use at home to give you an idea about whether your body composition is improving.
Tracking Body Circumference
One technique is tracking the circumference of different body parts.
You may have had your waist circumference measured with a flexible tape measure at the doctor’s office.
At home, you can also track the circumference of other body parts, such as the hips, arms, legs or chest.
You can make these measurements using a cheap, flexible tape measure.
While a change in circumference doesn’t exactly tell you if your fat mass or fat-free mass is changing, it can give you an idea.
For example, decreases in waist circumference are typically a sign that you are losing belly fat.
Gram for gram, fat takes up more space than muscle. This means your waist circumference may decrease when you lose fat, even if your weight doesn’t change.
If you’re exercising with weights, increases in arm circumference may mean that you are gaining muscle in your arms.
Of course, it is very important to measure the same way each time so that you get more accurate results.
Taking Progress Pictures
Progress pictures are another popular way to get a big picture look at your body composition.
It is often difficult to notice changes in your body from one day to the next.
However, taking pictures of your body every few weeks or months can be one way to assess how your body is changing.
This doesn’t give you exact information, but it can give you a general idea of differences in your size and shape.
Devices That Measure Body Composition
In addition to these simple methods, there are devices you can buy that measure body composition.
Many of these devices use a technology called bioelectrical impedance analysis (BIA).
BIA sends small electrical currents through your body to see how much your body resists the current. This information is used to predict your body fat percentage.
While it is nice to see an actual number for your body fat percentage, many of these devices aren’t very accurate.
In fact, research has shown that the common handheld BIA unit underestimates body fat percentage by 8–10%, compared to more accurate research tools.
What’s more, factors like food and water intake before using these devices can make the results inaccurate.
If you do choose to use a BIA device, be sure to use it in the morning before you eat or drink anything.