The Big 3 · DEXA + RMR + VO2 Max
Three tests. The complete picture of your health.
Wearables guess. Scales lie. Blood work only tells part of the story. The Big 3 measures what actually decides how you look, feel, perform, and age: what you're made of (DEXA), what you burn (RMR), and how fit you really are (VO2 Max). All three are available at DEXASCAN.COM locations nationwide — often in a single appointment.
Find Big 3 testing near me → See the three testsMeet the Big 3
Why people book the Big 3
These are the real reasons clients walk through the door — see if one of them is yours.
"The scale says I'm losing weight, but losing what?"
Weight loss can be fat, muscle, or water. DEXA is how you make sure the weight you're losing is fat — and this is the most common surprise on follow-up scans. On a GLP-1, it's non-negotiable: rapid loss without protein and lifting can take your muscle with it.
"I'm doing everything right and nothing's changing."
Plateaus are usually math problems. If your real RMR is 300 calories lower than the app's estimate, "everything right" is quietly a maintenance diet. One measured number typically explains the stall — and fixes it.
"I want to age on my own terms."
Longevity researchers point to the same short list: cardiorespiratory fitness, muscle mass, visceral fat, and bone density. The Big 3 measures all four — and the experts' advice is to baseline in your 30s or 40s, before muscle loss and visceral fat quietly accumulate.
"My wearable gives me numbers. I don't trust them."
Wrist-based VO2 and "body battery" scores are estimates built on estimates. The Big 3 is measured with clinical-grade equipment — the same category of testing that consumer devices are validated against.
"I'm training for something."
VO2 max testing maps your personal heart-rate zones and thresholds so every session has a purpose, and RMR nails your fueling. Racers tell us it removes all the guesswork from nutrition and training zones.
"My family history scares me."
Visceral fat, low muscle mass, low bone density, and poor cardio fitness are all risk factors you can see coming — and change. A baseline today turns "I hope I'm okay" into a number, a target, and a re-test date.
What each test decides
More data isn't automatically better — useful data changes a decision. Here's the decision each test drives:
| Test | The question it answers | The decision it changes |
|---|---|---|
| DEXA | What am I made of, and is it moving the right way? | Whether your program is working — cut, build, or protect muscle |
| RMR | How many calories do I actually burn at rest? | Your daily calorie and protein targets — measured, not estimated |
| VO2 Max | How fit is my engine, and what are my zones? | How you train — Zone 2 volume, intervals, and a longevity target to beat |
Do all three in one visit.
Many DEXASCAN.COM locations offer DEXA + RMR and DEXA + VO2 max bundles — the complete Big 3 baseline, typically for less than the cost of one boutique "full-body" scan.
Find a Big 3 location near you
Use the locator to find DEXA, RMR, and VO2 max testing in your area — then book directly from the location's page.
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Your Big 3 cadence
- DEXA: baseline now, re-scan every 90 days. Many clients run 4 scans a year and track weekly at home with a body composition scale.
- RMR: baseline now, re-test during an active program or after any 10–15 lb change — your metabolism moves as your body does.
- VO2 Max: baseline now, re-test every 3–6 months to watch your fitness age drop.
Want help reading your results? Every scan comes with our free guide, How to Read Your DEXA Report — and the 90-Day Plan to Change It, and our team can point you to the right re-test schedule for your goal.
Frequently asked questions
Can I really do all three in one appointment?
At many locations, yes — DEXA and RMR are both resting tests, and VO2 max takes 10–15 minutes of exercise. Plan about an hour for the full Big 3. Check your location's listing for available bundles.
How should I prepare?
Come fasted 4+ hours (overnight is ideal), skip caffeine and hard exercise beforehand, stay hydrated, and wear athletic clothing without metal. That preparation covers all three tests at once.
Is DEXA safe?
Yes — DEXA uses extremely low-dose X-ray, a fraction of everyday background exposure, and takes about 10 minutes. Pregnant individuals should skip DEXA as a precaution.
Do I need to be fit to take a VO2 max test?
No. Tests are graded to your level, and submaximal options (finishing at 80–90% effort) are available for anyone with physical limitations or preferences. You'll still get your zones and an accurate fitness picture.
What does it cost?
DEXA scans start at $99, with RMR and VO2 max bundles priced by location — typically the full Big 3 costs less than a single boutique full-body scan. Pricing is shown on each location's booking page.
Know what you're made of. Know what you burn. Know how fit you really are.
Invest in your health. Optimize your future.
Testing is for wellness and fitness tracking and is not a medical diagnosis. Consult your physician about any health finding, and before starting a new nutrition or exercise program — especially before a maximal-effort VO2 test if you have a cardiovascular condition.