This article explores the basics of body composition and BIA. To learn more about the advanced Segmental Body Composition feature unique to the BodyScan 2 health station, please see our dedicated article. 

What is body composition? 

You’ve probably seen the term body composition in a magazine before, but what does it mean? Body composition refers to the proportion of fat mass, muscle mass, bone mass, and water mass that make up your body. Understanding how each of these components are distributed in your body can help you better understand your overall health and fitness.

The total weight of body fat you carry is known as fat mass. Fat has an important role in the body as it helps regulate temperature, stores energy, and is important to managing hormones. Too much fat can be linked to health issues like high blood pressure, diabetes, and heart disease. Having too little fat, on the other hand, may also be linked to some health issues including low bone density or fertility issues.

Muscle mass refers to the weight of muscle in your body. Muscles are like the engines of our body as they play an important role in our metabolism and affect our overall health, function, and fitness.

Bone mass is the total weight of bones you have in your body. Bones are important because they protect our organs and store about 99% of our body’s calcium. 

Body water is the total amount of fluid in your body. It includes both intracellular and extracellular water (water both inside and outside of the cells).

Note that: Fat mass + Bone mass + Muscle mass = Weight 
Since there is water in muscle and fat, the water mass is not added to the other metrics when calculating your weight.

Knowing your body composition provides more information than just weight or body mass index (BMI), which don’t take into account muscle and fat mass. Even if your weight does not change, you may have changes in your body’s fat or muscle mass that are important to your health and fitness progress. 

How should I weigh myself to have accurate body composition measurements?

It’s best to weigh yourself regularly, at the same time and under the same conditions. This is because body composition results will vary during the day due to factors such as the amount of water in the body. It is also recommended to weigh yourself in the morning with an empty bladder.

Long-term trends in weight and body composition are more important than day-to-day changes.

Please see our article for the best practices for taking segmental body composition measurements.  

How does my scale measure body composition? 

The scale uses "bioelectrical impedance analysis" (BIA), a simple and non-invasive test, to measure body composition. 

A small, safe current is induced in the lower half of the body. A higher body fat percentage will create more resistance for the electrical current. By measuring the resistance of the different types of body tissues to the flow of this current, the scale can estimate the body composition of the user.

Important note: The current used for body composition is a very low voltage that is considered safe for general use. However, it is recommended that pregnant people and people with pacemakers, ICDs, or other implanted electronic devices should not use this device or should disable this feature in the app.

If you want to learn more about BIA and how it measures body composition, please follow this link: https://www.withings.com/us/en/health-insights/about-bioelectrical-impedance-analysis