List two ways to determine percent body fat. Describe a limitation of each method.

Name: Problem 7, Chapter 19: Chemistry for Changing Times
Uploaded: 2021-11-04T23:47:25-08:00
Duration: 3 min 38 s
Channel: Crystal Wang
Description: List two ways to determine percent body fat. Describe a limitation of each method.

step 1 So let's look for two ways that we can estimate percentage body fat. So the first way is when we

List two ways to determine percent body fat. Describe a...

Key Concepts

Hydrostatic Weighing

Hydrostatic weighing is a method that determines body fat percentage by measuring body density. It involves weighing a person underwater and on land to calculate the difference, which can then be used to estimate fat mass versus lean mass. This technique is considered accurate but its limitations include the requirement for specialized and often expensive equipment, discomfort during submersion for some individuals, and potential inaccuracies if the subject does not expel all air from their lungs during the test.

Bioelectrical Impedance Analysis

Bioelectrical Impedance Analysis (BIA) estimates body fat percentage by sending a low-level electrical current through the body and measuring the resistance encountered. Since fat and lean tissue conduct electricity differently, this resistance can be used to estimate the proportion of body fat. However, BIA's accuracy can be limited by several factors such as the subject's hydration status, recent food intake, and skin temperature, all of which can cause variability in the measurements.

Transcript

00:01 So let's look for two ways that we can estimate percentage body fat.

00:05 So the first way is when we measure a person's density.

00:14 So what we do is we will weigh the person to get the mass and the volume will be calculated using a dunk tank.

00:25 So it's similar to using water displacement to get a volume for an irregular object.

00:33 So that's basically the concept that they're applying here.

00:38 The mass, the difference between a person's weight in air and when submerge and water corresponds to the mass of the displaced water.

00:54 So the person has a certain weight in the air, which we got, which is just the mass.

00:59 And when there's submerged water, the difference between the weight in air and the mass and water equals mass of displaced water.

01:10 So then we'll take the mass, divide that by the density of water, and it gives a reasonable value for that person's volume.

01:22 So again, we're just kind of applying the concept of measuring the volume of an irregular object.

01:28 Except now we don't really have any markings to measure the volume with.

01:33 That's why we have to use this method to find the difference between the weight of the person in air.

01:43 And submerge in water because we don't have those markings.

01:46 So then we have the mass divided by volume, and that gives us the density, because density is able to mass divided by volume...

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