Key facts
- Found in smart scales and handheld devices.
- Fast, cheap, and non-invasive.
- Readings shift with hydration and food.
- Best for tracking trends, not absolute precision.
BIA works because fat, muscle, and water conduct electricity differently. A tiny, unnoticeable current is passed through the body, and the device estimates body fat from how much resistance it meets. It's the technology behind most smart scales and handheld body-fat monitors.
Its appeal is convenience — instant, painless, and inexpensive. The catch is accuracy: readings are easily thrown off by hydration, food, and recent exercise, so a single number can be unreliable. Used consistently (same time, same conditions), BIA is more useful for tracking the direction of change than for a precise body-fat figure.
Frequently asked questions
Are bioelectrical impedance scales accurate?
They're only moderately accurate for a single reading, since hydration and food sway the result. They're more reliable for tracking trends when used under consistent conditions.
How do I get a consistent BIA reading?
Measure at the same time of day under the same conditions — for example, first thing in the morning, fasted, and before exercise — to make readings comparable over time.
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