# Body Fat Measurement Device Question
**URL:** https://boards.straightdope.com/t/body-fat-measurement-device-question/133526
**Category:** Factual Questions
**Created:** [October 23, 2002, 2:41pm UTC](https://boards.straightdope.com/t/body-fat-measurement-device-question/133526 "2002-10-23T14:41:20Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Jackknifed\_Juggernaut](https://boards.straightdope.com/u/Jackknifed_Juggernaut)
#### Post date: [October 23, 2002, 2:41pm UTC](https://boards.straightdope.com/t/body-fat-measurement-device-question/133526/1 "2002-10-23T14:41:20Z")
Yesterday, my office held a health fair. I went to get my body fat percentage measured. The technician asks me for my age (32), my height (5’10") and my weight (152). Then I grasp 2 handles on a device which spits out my body fat percentage (12%). A couple of people comment on how good that is, and I must admit that I’m feeling pretty proud.
Then I think to myself: “How did that device read all the fat throughout my body simply by me grasping the handles?” Was I duped? Did the age, height and weight answers imply my body fat %-age? Or did grasping the handles really do something magical? And how?
---
### Author:  [@Philster](https://boards.straightdope.com/u/Philster)
#### Post date: [October 23, 2002, 3:05pm UTC](https://boards.straightdope.com/t/body-fat-measurement-device-question/133526/2 "2002-10-23T15:05:50Z")
This was covered here:
Electrical impedence through water and fat.
Your age, height and weight and level of exercise/activity (are you an ‘athlete’?) all help the machine make sense out of the electrical impedence number that comes out.
My experience with those machines is: they suck.
If the machine is set wrong, someone with 20% body fat could be anywhere from 10-25% at the read out.