What is a Resting Metabolic Rate (RMR) test?

A Resting Metabolic Rate (RMR) test measures how many calories your body burns at rest by analyzing the oxygen you breathe. Every calorie your body burns requires a fixed amount of oxygen, so measuring your oxygen use (a method called indirect calorimetry) gives you your real resting calorie burn instead of a formula's guess.

At Body Fat USA in Denver, an RMR test costs $100 ($175 with a DEXA scan), the appointment takes about 20 minutes, and you leave knowing your number.

  • Price: $100, or $175 with a full-body DEXA scan
  • Appointment: 20 minutes (about 10–15 minutes of relaxed breathing)
  • Equipment: KORR metabolic analyzer—indirect calorimetry, the same principle used for metabolic testing in hospitals
  • Preparation: water only for 4 hours, no caffeine, no exercise beforehand
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Why test your metabolism?

Your RMR is the largest part of the calories you burn each day. Knowing it lets you and your coach, dietitian or physician set calorie targets around your body instead of an average. An RMR test can help you:

  • Set accurate calorie targets for fat loss, maintenance or muscle gain
  • Troubleshoot a weight-loss plateau and check for metabolic adaptation after long periods of dieting. Plateau or metabolic adaptation?
  • Screen for a slower-than-expected metabolism that may explain past frustration
  • Set a maintenance target once you reach your goal so you can keep your results
  • Track changes over time, especially during GLP-1 medication weight loss or after gaining muscle

Pair your RMR with a DEXA scan to see how much of your weight is lean tissue—the tissue that drives most of your resting calorie burn.

How the RMR test works

  1. Arrive rested. Sit back in a comfortable reclined position (and enjoy our 11th-floor view of the mountains and the University of Denver).
  2. Breathe normally. You breathe through a new, single-use KORR mouthpiece while a nose clip makes sure every exhaled breath is analyzed. One-way valves mean you only inhale fresh room air.
  3. Relax for about 10–15 minutes. Close your eyes and keep your lips sealed lightly around the mouthpiece while the analyzer measures your oxygen consumption.
  4. Get your number. Your results show your measured resting calories per day, and we explain how to use them.

Learn more: How is RMR measured? · What is resting metabolic rate?

How to prepare for your RMR test

  • Fast for at least 4 hours. Water only—no food, coffee, tea, sugar-free gum, mints or energy drinks.
  • No caffeine, nicotine or other stimulants before your test.
  • No exercise on the day of your test until after your appointment.
  • Arrive relaxed and rested. Stress, poor sleep and illness can all change your result.
  • Repeat tests under the same conditions (time of day, fasting window) so comparisons are meaningful.

Missed the fast? Call us at (303) 758-9552 and we will help you reschedule. More details: What should you do before an RMR test?

Why not just use an online calculator?

Predictive formulas were built from population averages because direct measurement used to be expensive. For any one person they can be off by 10% or more. A 10% error on a 2,000-calorie day is 200 calories—enough to add up to roughly 20 pounds over a year if you set your diet around the wrong number.

Two people with the same age, height and weight can have meaningfully different metabolisms. Measuring yours removes the guesswork. Can online calculators estimate my metabolism?

RMR testing FAQ

A Resting Metabolic Rate (RMR) test at Body Fat USA is $100, or $175 when combined with a full-body DEXA scan. No membership or package is required.

Plan on a 20-minute appointment (30 minutes if you add a DEXA scan). The breathing measurement itself takes about 10–15 minutes while you sit back and relax.

Yes. Have nothing but water for at least 4 hours before your test—no food, coffee, tea, sugar-free gum or energy drinks—and avoid caffeine and other stimulants that day.

No. Avoid exercise on the day of your test until after your appointment. Working out afterward is fine.

Usually, yes. Calculators such as Harris-Benedict or Mifflin-St Jeor estimate from population averages and can miss an individual by hundreds of calories a day. An RMR test measures your oxygen use directly.

BMR (basal metabolic rate) is measured under strict laboratory conditions, often after an overnight stay. RMR is measured at rest under practical conditions and is very close to BMR for most people, which is why it is the standard test in fitness and nutrition settings.

Book your RMR test in Denver

Body Fat USA · 1776 S Jackson St, Suite 1111 (11th floor), Denver, CO 80210 · Free parking · Monday–Friday, 7:00 a.m.–4:00 p.m. · (303) 758-9552

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