Body fat scales measure body fat using a technology called bioelectrical impedance analysis (BIA). Here's how they work:
- When you step on the scale, sensors under your feet send a very weak, harmless electrical current through your body, typically traveling up one leg, across the pelvis, and down the other leg.
- This electrical current encounters different levels of resistance (impedance) depending on the type of tissue it passes through. Fat tissue contains less water and therefore resists the current more than muscle or other lean tissues, which have higher water content and conduct electricity better.
- The scale measures how much resistance the current experiences as it travels through your body.
- Using this impedance measurement, along with personal data you input such as age, gender, height, and weight, the scale estimates the percentage of your body that is fat versus lean mass.
- Some advanced scales can sync this data with smartphones or fitness apps for tracking over time.
Because fat and muscle differ in water content and electrical conductivity, the scale uses the resistance data to calculate an estimate of body fat percentage
. However, these scales provide only rough estimates rather than precise measurements. Factors such as hydration level, recent meals, body fat distribution, age, gender, and physical activity can affect the readings. Therefore, body fat scales are most useful for monitoring trends over time rather than giving an exact body fat percentage at a single measurement
. In summary, body fat scales measure body fat by sending a small electrical current through the body, measuring the resistance encountered, and using that data combined with personal information to estimate body fat percentage via bioelectrical impedance analysis.
