The bathroom scale has one number and it hides the truth. It can’t tell you if a five pound change is fat, muscle, or water. It can’t tell you if the muscle on your left side matches your right, or whether your metabolism is running the way it should. That’s usually what sends people searching for a better test, and the search tends to turn up the same two names: InBody and DEXA. Both measure body composition. They work differently, cost differently, and fit different goals. Here’s a plain English comparison so you can pick the right one for your goal, your budget, and howoften you actually want to retest.
What is the difference between InBody and DEXA?
DEXA uses a low dose X-ray to scan your whole body and is often treated as a reference method for body composition research. InBody uses bioelectrical impedance, a small painless electrical current, to estimate the same thing. InBody is faster, involves no radiation, and is easier to repeat often.
A DEXA scan sends X-ray beams at two energy levels through your body and measures how much each tissue type absorbs. That difference in absorption is what separates bone, fat, and lean tissue in the final readout. It’s the same core technology used to check bone density, which is why DEXA is the gold standard whenever bone health is part of the question.
An InBody scan works differently. You stand on a platform and hold two handles while a low level current runs through five segments of your body: each arm, each leg, and your trunk. Muscle conducts that current easily because it holds more water. Fat resists it. The machine reads those differences and calculates your composition from there, usually in under a minute, with no bone density reading involved at all.
Accuracy, consistency, and what skews results
For tracking progress over time, consistency usually matters more than one off precision. A single InBody reading that’s slightly off in one direction isn’t the problem. What matters is whether your results are measured the same way every time, so the trend line actually means something.
Bioelectrical impedance readings can shift based on hydration, recent meals, time of day, and whether you trained hard the day before. Research on BIA methods, including the the foundational review by Kyle and colleagues in Clinical Nutrition, has long noted that hydration status is one of the biggest sources of variability in impedance based measurements. That’s not a flaw unique to InBody. It’s just how the technology works, and it’s why consistent testing conditions matter so much.
A simple pre scan checklist helps keep your numbers comparable from one test to the next:
- Test at the same time of day each time, ideally morning before eating
- Skip hard training or a sweaty workout right before the scan
- Keep your hydration normal and consistent, not dehydrated and not overloaded with fluids
- Use the bathroom beforehand and skip lotion on your hands and feet
DEXA has its own sources of variation too, including scanner calibration and positioning, though it’s generally considered more precise for a single snapshot measurement. The practical difference is this: DEXA may edge out InBody for a one time, highly precise reading, while InBody’s speed and radiation free design make it the more realistic choice for regular retesting.
Think of it this way. A scale that’s accurate to the ounce doesn’t help much if you only step on it once a year. A slightly less precise tool you actually use every month will tell you more about your real progress. That’s the trade off between these two tests in a nutshell.
Comparison table: InBody vs. DEXA
| What you’re comparing | InBody | DEXA |
|---|---|---|
| Technology | Bioelectrical impedance analysis | Dual energy X-ray |
| Radiation | None | Low dose X-ray |
| Time per scan | Under a minute | Roughly 10 to 20 minutes |
| What it measures | Segmental lean mass, body fat percentage, visceral fat level, body water | Lean mass, fat mass, and bone density |
| Best use | Frequent progress tracking | High precision snapshot, bone density questions |
| How often you can retest | Every few weeks with no added risk | Limited by radiation exposure guidelines |
| Where to get it in Portland | Hyatt Strength + Wellness in NW Portland | A medical imaging provider or physician referral |
Which test should you choose?
The right test usually comes down to your goal. If you’re tracking muscle gain or fat loss every six to eight weeks, InBody fits better. It’s fast, repeatable, and there’s no radiation limit to worry about with frequent testing. If you have a specific bone density question, a medical referral, or a condition your physician wants to monitor, DEXA through a medical provider is the better fit. And if you’re tracking weight loss on a GLP-1 medication, either test can work well when it’s paired with a coach who helps you interpret the numbers and adjust your plan.
Worth saying plainly: Hyatt Strength + Wellness does not offer DEXA on site. If bone density data is what you need, ask your physician about getting a DEXA scan through a medical provider. We’re not going to pretend otherwise just to keep you in the building.
If you want the fuller picture on why body composition testing matters in the first place, our body composition guide (coming soon!) covers the basics before you ever book a scan, and our post on track progress beyond the scale (coming soon!) goes deeper into non-scale ways to measure whether your training is working.
How InBody scans work at Hyatt Strength + Wellness
At our NW Portland studio, the InBody 570 scan takes under a minute once you’re set up on the platform. You’ll get a printed breakdown showing your skeletal muscle mass, body fat mass, segmental lean mass for each arm, leg, and your trunk, visceral fat level, and body water balance, all in pounds and percentages you can actually read.
Coaches use that printout to do more than hand you a number. A segmental imbalance between your right and left leg might shape how a trainer programs your next block. Your basal metabolic rate, calculated from your lean mass, becomes a starting point for nutrition coaching targets. Most members retest every eight to twelve weeks under consistent conditions, which is often enough time for a program to produce a measurable change without testing so often that the numbers get noisy. One InBody printout alone won’t tell you much. What your coach does with it over a few scans is where the actual value shows up.
The test you’ll actually repeat
The best body composition test isn’t necessarily the most precise one. It’s the one you’ll repeat consistently and actually act on. For most people training toward a fitness goal, that’s InBody: fast, radiation free, and built for regular retesting. For a specific medical or bone density question, talk to your physician about DEXA instead. And if you’re still weighing body composition testing against the number on the scale at all, our post on body composition vs. BMI covers that comparison directly.
Want to know your real starting point? Book an InBody scan at our NW Portland studio.
Author Jeremy Hyatt, MS, CSCS is a personal trainer and co-owner of Hyatt Strength + Wellness. He believes it’s important to start with the basics and move from there. Too often, people get into complicated movements and goals before they have the proper fundamentals, which can lead to negative results. Jeremy has been working in the fitness industry since 1995 and co-founded Hyatt Strength + Wellness in 2011.
Learn more about Jeremy, or get in touch with him by emailing us at Go@HyattGym.com.
Hyatt Strength + Wellness is a team of certified, enthusiastic and innovative health and fitness professionals in Portland, Oregon. Get in touch by emailing us at Go@HyattGym.com.
