A body fat scale determines the body fat percentage by measuring the bioelectric resistance. The bioelectrical impedance analysis makes use of the fact that different body tissues (body fat, musculature, bones) build up different resistances when current flows through. An electrical signal travels from one foot to the other. The greater the resistance, the higher the body fat percentage. Adipose tissue blocks or obstructs the signal, while muscles quickly transmit the signal.
The difference in conductivity is due to the different water content of fat and muscle. Muscles consist of 70 percent water, while fat contains only 5 to 13 percent water. Taking into account body size, weight, age, and gender, the proportion of lean and fat mass can be determined.
The currents used are not noticeable and harmless to health. The bioimpedance measurement uses an alternating current with a high frequency (5 to 100 kHz).
Risks and side effects of a body fat scale
A body fat balance and other bioimpedance equipment should not be used by pregnant women and people with a pacemaker. The current flow could affect the pacemaker.
The accuracy of the measurement results of a body fat scale
The error rate of body fat scales is very high. There are multiple reasons for this:
- The current is only passed from one leg to the other and not through the entire body. (Foot to foot measurement). As a result, only the body fat percentage of the lower half of the body is measured.
- Dehydration z. B. after training or alcohol consumption falsifies the result since at a lower salt and liquid level in the body, the current is conducted worse.
- Sweaty or creamy feet can falsify the measurement result.
What should be considered with a body fat scale:
To determine as accurately as possible the body fat percentage with a body fat scale, you should always measure at the same time of day. The last food and drink intake should be the same long ago. Only the results of one and the same body fat scale are comparable. The result is of little importance due to the high degree of inaccuracy. Meaningful, however, is a long-term change in body fat levels.
In women body, fat measurement with a body fat scale is due to the monthly cycle to fluctuations.