Which body composition measurement method is best for you?

Body composition measurements tell more about your health than weight alone. Learn the pros and cons of different body composition measurement methods to find the best option.

Which body composition measurement test is best?

Your body composition—how much of your body is fat versus muscle, bone, and water—is a valuable indicator of progress in your health journey. But how do you measure it? There are several body composition measurement options, each with pros and cons. Let’s break them down.

DEXA scan

Originally designed to measure bone density, DEXA (Dual-Energy X-ray Absorptiometry) is one of the most precise ways to measure body fat and muscle mass. You lie down while a scanner moves over your body, giving you a detailed breakdown of fat, muscle, and bone in different areas of your body.

How is a DEXA scan performed?

The test is performed in a medical facility by trained technicians. It is a noninvasive, painless procedure that lasts about 20 minutes. A radiology technician assists you through the process. Wearing metal-free clothing or a hospital gown, you lie on your back on an X-ray table. Once the test starts, you must remain completely still while the technician moves a large scanning arm over your body. The test is safe with minimal radiation exposure.

✅ Pros:

• Extremely accurate (one of the best methods available)
• Gives you detailed info on fat distribution (not just a total percentage)
• Also checks bone health
• Compares the right and left sides of the body, looking for imbalances in muscle development due to injury or usage

❌ Cons:

• Expensive
• Requires a medical or sports facility visit
• Exposes you to a minimal amount of radiation
• Not recommended for pregnant women

Best for: People who are serious about getting precise data and don’t mind the cost

Underwater weighing (hydrostatic weighing)

This method involves—you guessed it—getting "dunked" in a water tank. Because fat floats and muscle sinks, your submerged weight helps determine your body fat percentage based on body density. It occurs in special pools and/or water tanks designed for hydrostatic measurement. The test is usually only available at universities, research facilities, and certain fitness centers.

How is underwater weighing performed?

Before weighing under water, you are weighed outside the water. Then, wearing a bathing suit, you enter a pool or tank and sit in a submerged chair. The chair is lowered into the water, or you lower your head until your entire body is submerged. Then, you exhale as much air as possible by blowing bubbles. The recorded weight gets plugged into equations to calculate body composition.

✅ Pros:

• Highly accurate
• Doesn’t require radiation or electrical currents

❌ Cons:

• Requires going to a special facility; limited locations
• Involves getting wet and submerging underwater

Best for: Those who want a highly accurate method and don’t mind a bit of a hassle

Bioelectrical Impedance Analysis (BIA)

BIA is available in many home bathroom scales and some handheld devices at the gym. It works by sending a low-level, harmless electrical current through your body. Since fat slows down the signal more than muscle, the device estimates your body fat percentage based on how fast the signal moves.

How is BIA performed?

You stand barefoot on a special scale and possibly hold hand electrodes while the device sends the electrical current through your body, delivering results in seconds.

✅ Pros:

• Convenient—you can do it at home!
• Quick and painless
• Affordable

❌ Cons:

• Results can vary depending on hydration, food intake, and time of day
• Not as precise as other methods
• Can be misleading if you have a lot of muscle
• Those who have a pacemaker or other implanted cardiovascular device should avoid BIA

Best for: People who want a simple way to track trends over time rather than precise numbers

BOD POD (air displacement plethysmography)

The BOD POD is an egg-shaped chamber that measures how much air your body displaces to estimate body composition.

How is BOD POD testing performed?

You wear minimal, form-fitting clothing and sit quietly inside the sealed chamber for a few minutes to get your results.

✅ Pros:

• Comfortable—no pinching or electrical currents involved
• Good accuracy
• Quick
• Somewhat accessible, becoming more common in weight loss clinics and gyms
• Accurate for all ages from age 2 years and older

❌ Cons:

• Requires a visit to a special facility
• Confined space
• Does not indicate the distribution of body fat
• Can be expensive
• Requires tight-fitting clothing similar to workout wear

Best for: People who want a compromise between convenience and accuracy, and are willing to go to a testing center

So, which body composition measurement method should you choose?

Suppose you want a quick and easy way to track trends, then go with BIA (a smart scale at home will do the trick). The BOD POD is an excellent choice for accuracy without a super price tag. DEXA is the gold standard if you’re all about precision and have the budget. And if you want to geek out on science and don’t mind getting wet, underwater weighing could be fun!

Whatever method you choose, the most important factor is consistency. Use the same method each time to track progress over weeks and months.

Monitoring body composition changes with MyNetDiary

No matter which method you choose, you can track your body composition progress over time with MyNetDiary with My Health under the “Me” tab. You can track body fat percentage, muscle percentage, body measurements, and more.

Whether you are starting a new exercise or weight-loss plan, consider a body composition test at the beginning of your program and track it in the app. Then, after a few months, get another test to see how your body composition changes. Since muscle is denser than fat, the scale may show that your weight is unchanged, but a lower body fat percentage means progress toward a healthier you.

Related content

What is the difference between BMI and body fat percentage?

Measure success beyond the scale to track weight-loss progress

7 factors that affect body composition

Still new to MyNetDiary? Learn more today by downloading the app for FREE.

Weight Loss->Body composition