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| Galaxy Watch 4 calculates body fat percentage |
The new connected Galaxy Watch 4 from Samsung has a function of calculating body fat percentage and muscle mass.
Samsung is the latest technology company that provides body composition function. It came to Amazon, which provides a body fat percentage function through the Halo Band.
Compared to body weight, body fat is generally a better way to measure health. But it is usually calculated using a method called body mass index (BMI), which is not accurate.
The Galaxy Watch 4 uses a technology called bioelectrical impedance analysis (BIA) to measure body composition, which sends a small electrical current through the body.
This technique calculates the amount of water in the body because the signal travels faster through tissues with higher water content.
Since fat contains less water than muscle, this technique can estimate a person's fat content.
BIA can give an estimate of body fat. But it has limits. There is no perfect relationship between the amount of water in the body and body fat.
Over time, the amount of water in the body changes. For example, it can fluctuate up and down during exercise or when someone drinks a lot of water.
One study found that BIA may overestimate body fat if measured immediately after drinking about two glasses of water.
Most devices that use BIA to track body composition send electricity through the soles of your feet (such as smart scales) or the palms of your hands.
Galaxy Watch 4 calculates body fat percentage
Samsung designed the sensor to fit on the back of the watch. The company's health lab published a study describing the technology in January 2021.
During the study, the watch and two other BIA devices analyzed the body composition of 203 people. Except for the use of dual energy X-ray absorptiometry (DXA) devices. It is an X-ray technique that shows the distribution of fat in the body. This is considered the gold standard for measuring body composition.
The analysis showed that the smartwatch is accurate compared to the DXA measurement. His calculations are also closer to DXA measurements than other BIA measurements.
Samsung's method differs from Amazon's Halo body composition analysis feature. Only body fat does not matter to muscle.
The app guides users to take pictures of their bodies which are combined into 3D images to calculate their body fat percentage. According to an Amazon-funded study, the system can also more accurately measure body fat compared to DXA.
Both apps appear to be more effective than BMI in calculating body fat percentage.
BMI is used to guide medical decisions. While this is often misleading, in some cases it can falsify the diagnosis.