How to Read a Body Composition Analysis (And Why Your Weight Tells You Nothing)

By Tina Chagoury, Clinical Dietitian · 5 min read · 2026-08-24

When I look at your body composition, I can tell what you have been doing. Here is how to read your own.

When I look at a woman's body composition analysis, I can usually tell what she has been doing. Whether she has been eating properly. Whether she has been lifting. Whether she has been taking her supplements. It tells a great deal of the story.

Here is how to read your own.

How the machine works

These devices use a technology called bioelectrical impedance. They send a very small electrical current through the body and measure how tissues conduct it.

Muscle, which holds a high proportion of water, conducts quickly. Fat conducts far more slowly. From the difference, the machine calculates your proportions.

What it reports, and what to look at

Fat mass and fat percentage

Look at whether it is too high or too low. Very low body fat harms hormonal function. Very high body fat, particularly visceral fat, promotes inflammation.

But the number on a single day matters far less than the direction it moves.

Muscle mass, the most important figure

Especially for women. Two things matter here: how much muscle you started with, and how it is changing.

Muscle tells me a great deal. It indicates whether insulin resistance is likely, whether your metabolic rate is healthy, and whether you are actually responding to the protocol you have been given.

Visceral fat, with a caveat

The machine does not truly measure visceral fat. It provides an estimate. Useful as a trend, not as a precise value.

Total body water

If your muscle percentage is high, your total body water will naturally be higher than average, and that is normal. What matters is the change over time. A sharp drop may indicate dehydration. A sharp rise may indicate inflammation and fluid retention.

Intracellular and extracellular water

If your machine reports these separately, this is genuinely useful. You want the water inside the cells to be the larger share. Water outside the cells is an indicator of inflammation or water retention.

What to ignore

Weight on its own tells you nothing.

BMI on its own tells you almost nothing. Body mass index is simply weight against height. Your weight could be almost entirely fat, or predominantly muscle, and BMI cannot tell the difference.

Daily fluctuations. These machines are not accurate enough day to day to be worth reading that closely. You will drive yourself mad watching numbers that reflect hydration and meal timing rather than any real change.

How often to measure

Every two to three weeks is sensible. That is frequent enough to see a genuine trend and infrequent enough to avoid noise. Then we look at what changed and adjust the protocol accordingly.

That is the whole purpose. Not to judge the number, but to use it to decide what to do next.

This article is nutrition education, not medical advice.

Tina Chagoury is a licensed clinical dietitian specialising in women's hormonal health and metabolism, and the creator of the Hormone Reset Method™. Learn more and start here.