Longevity & Performance · Orchard, Singapore
Resting Metabolic Rate (RMR) Testing in Singapore
A 15 minute measurement of how many calories your body burns at rest, taken by indirect calorimetry at Hisential Orchard. No exercise is involved. Your own oxygen consumption is measured instead of estimated by a formula, and a doctor turns it into a daily energy target read alongside your body composition and bloods.
Verified by Dr. Anthony Stanislaus, MBBS, PBM, Cert. Men's Health · Last reviewed 12 August 2026 · Next review 12 February 2027
What RMR testing measures
Resting metabolic rate is the number of calories your body burns simply keeping you alive: breathing, circulation, brain activity, kidney function and cell repair. For most people it accounts for around 60 to 70 per cent of total daily energy use, which makes it the largest single component of your calorie needs and the one worth measuring accurately.
It is measured by indirect calorimetry. Your oxygen consumption and carbon dioxide production are recorded while you rest, and energy expenditure is calculated from those gas volumes. Standardised conditions, a proper rest period and a fasted state are what make the reading reproducible.[4]
The measurement also reports your respiratory exchange ratio, which indicates the balance of fat and carbohydrate your body is using as fuel while at rest.
How it is done
- You rest quietly for around 15 minutes, reclined, in a calm room.
- You then breathe normally into a metabolic analyser. Nothing is strenuous and no exercise is involved.
- The measurement itself takes about 15 minutes.
- Testing is done fasted, first thing in the morning where possible, for a stable reading.
- A doctor reviews the result and reports it as your metabolic baseline with a daily energy target.
Why metabolism matters for healthspan
Healthspan is the number of years you spend in good functional health. Two of the strongest influences on that are body composition and metabolic health, and resting metabolic rate sits where the two meet: it is largely determined by how much metabolically active lean tissue you carry.[6]
Muscle is not only for strength. It is the body's main site of glucose disposal and a reserve drawn on during illness and recovery, and its loss with age tracks with frailty and slower recovery. A resting metabolic rate that drifts downward over years, when body weight has not changed, is often the earliest quantitative sign that lean tissue is being lost.[6]
Metabolic rate is also sensitive to hormonal change. Thyroid hormone is a principal regulator of resting energy expenditure, so an unexpectedly low or high measurement can be the prompt for a doctor to look at thyroid function and other bloods.[7]
Ageing research has examined resting metabolic rate in both directions, with some cohort work reporting that a higher rate in older adults tracks with mortality risk while very low rates accompany loss of lean tissue. The honest reading is that RMR is a physiological marker to be interpreted in context, not a score to maximise or minimise.[5]
These findings describe patterns observed across populations. They are not a prediction about any individual. What the measurement gives you is an accurate starting point and a way to see whether what you do next moves it.
Measured against predicted
Most calorie targets come from a predictive equation such as Harris-Benedict or Mifflin-St Jeor, using height, weight, age and sex. Those equations were built to be accurate on average across a population. A systematic review comparing them against measured values found that even the best performing equation fell within 10 per cent of the measured figure in only around 70 per cent of non-obese adults, and fewer of those with obesity, with individual errors running several hundred calories a day in either direction.[1], [2]
For someone planning a deficit or a surplus, a few hundred calories is the whole intervention. That is the case for measuring rather than predicting.
Resting energy expenditure is also not fixed. Follow-up of participants after substantial weight loss documented resting metabolic rates that remained several hundred calories a day below the level predicted for their new body size, persisting years later.[3] Measuring your current rate, rather than assuming the rate you had before, is what keeps a plan realistic.
Predicted
A formula based on height, weight, age and sex. Free, instant, and accurate for a population average rather than for you. Body composition, thyroid status, dieting history and training are not inputs.
Measured
Your own oxygen consumption and carbon dioxide production, taken at rest under standard conditions. Repeatable, comparable over time, and specific to your current physiology.
Reading your RMR report
Measured resting calories per day
Your headline figure: the energy your body uses at complete rest over 24 hours, measured rather than predicted.
Measured against predicted
The same figure alongside what a standard equation would have assumed for you, so the size and direction of the gap is visible.
Respiratory exchange ratio
The balance of fat and carbohydrate your body is using as fuel at rest, which gives context to the calorie figure.
Daily energy target
Your resting rate scaled by your actual activity, then adjusted for your goal, whether that is loss, maintenance or gain.
Read with body composition
Lean mass is the main driver of resting metabolic rate, so the two are interpreted together rather than separately.
Doctor's interpretation
A plain-language summary noting anything that warrants further review, such as thyroid function where the figure sits well outside expectation.
What moves your resting metabolic rate
Resting metabolic rate is not fixed, but it does not swing on demand either. The factors below are the ones with real influence, and a repeat measurement is how you see which of them applied to you.
Lean mass
Muscle and organ tissue account for most of your resting energy use. Resistance training and adequate protein are the levers with the strongest evidence behind them.
Prolonged calorie restriction
Extended deficits are associated with a resting rate that sits below the level predicted for the new body size, and that gap can persist.
Thyroid function
Thyroid hormone is a principal regulator of resting energy expenditure, so under- or overactivity shows up in the measurement.
Age
Resting rate declines gradually with age, largely through loss of lean tissue rather than an intrinsic slowing of cells.
Illness and recovery
Fever, infection and recovery from surgery raise energy needs temporarily, which matters when nutrition is being planned.
Stimulants and medication
Caffeine, nicotine, thyroid replacement and some other medications change the reading, which is why preparation instructions are strict.
Who RMR testing is for
- Anyone managing weight who wants a calorie target measured rather than estimated by an app.
- People whose weight has stalled on a plan that should, on paper, be working.
- Patients who have lost significant weight before and want to know where their metabolism sits now.
- People building muscle who need an accurate surplus rather than a guess.
- Patients being reviewed for fatigue, cold intolerance or unexplained weight change, alongside bloods.
- Anyone taking a longevity screening package that includes metabolic measurement.
Test-day protocol and preparation
Before your test
- Fast for at least eight hours. Plain water is fine and encouraged.
- No caffeine, nicotine or supplements on the morning of the test.
- No exercise beforehand. Travel to the clinic without rushing where possible.
- Tell us about any medication, particularly thyroid replacement and stimulants.
- Morning appointments are preferred because the reading is most stable then.
On the day
- Around 15 minutes of quiet rest, reclined, before anything is recorded.
- Roughly 15 minutes of measurement while you breathe normally into the analyser.
- Body composition is usually measured in the same visit, since the two are read together.
- Where VO2 max is booked as well, RMR is done first while fasted.
- Allow about 30 minutes in total.
What the test does not tell you
- It is not a diagnostic test. An unexpected result may prompt further blood work, but the measurement itself diagnoses nothing.
- It measures resting energy use only. Your total daily expenditure also depends on activity and on the energy cost of digesting food.
- It is a snapshot taken under standard conditions. Poor sleep, illness, recent food or caffeine will shift the reading.
- It does not tell you what to eat. Translating the figure into a plan happens in the consultation with your doctor.
- Comparisons only hold when the test is repeated under the same fasted, rested conditions on the same analyser.
- It is not a measure of fitness. Cardiorespiratory capacity is assessed separately through VO2 max testing.
How to book
RMR testing can be booked on its own, or as part of The Helios and The Orion longevity tiers and the Performance Max and Weight Management Bundles. Pricing is provided by your personal concierge before you book, with the full cost confirmed up front.
Resting metabolic rate testing questions
Clear answers, written by our clinical team. Tap any question for its direct permalink, or reach out to your Personal Concierge for anything else.
It measures how many calories your body burns at rest by indirect calorimetry: your oxygen consumption and carbon dioxide production are measured while you lie still, and your energy expenditure is calculated from those gas volumes. The measurement takes about 15 minutes and involves no exercise.
An app applies a prediction equation based on height, weight, age and sex. Those equations are built to be accurate on average across a population, and published comparisons against measured values show individual errors of several hundred calories a day. An RMR test measures your own figure instead of estimating it.
A measured resting metabolic rate below the value a formula predicts can reflect lower muscle mass, a sustained period of calorie restriction, thyroid or other hormonal factors, or simply individual variation. It is interpreted alongside your body composition, blood results and history rather than read on its own.
A higher than predicted figure often reflects more lean mass than the formula assumes. Less commonly it can accompany thyroid overactivity, fever, or recent stimulant use. Your doctor reads it with your bloods and history before drawing any conclusion.
Fast for at least eight hours, with plain water encouraged. No caffeine, nicotine or supplements on the morning of the test, no exercise beforehand, and travel to the clinic without rushing where possible. You then rest quietly for around 15 minutes before the measurement begins.
Resting metabolic rate tracks closely with lean mass, so resistance training and adequate protein are the levers with the strongest evidence behind them. Crash dieting tends to move it the other way. We report what your rate is and what it does over time rather than promising a figure.
Still have a question?
Your Personal Concierge replies within one business day - confidentially.
References
- [1] Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association. 2005;105(5):775-789.
- [2] Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51(2):241-247.
- [3] Fothergill E, Guo J, Howard L, et al. Persistent metabolic adaptation 6 years after The Biggest Loser competition. Obesity. 2016;24(8):1612-1619.
- [4] Compher C, Frankenfield D, Keim N, Roth-Yousey L. Best practice methods to apply to measurement of resting metabolic rate in adults: a systematic review. Journal of the American Dietetic Association. 2006;106(6):881-903.
- [5] Ruggiero C, Ferrucci L. The endeavor of high maintenance homeostasis: resting metabolic rate and the legacy of longevity. Journals of Gerontology Series A. 2006;61(5):466-471.
- [6] Wolfe RR. The underappreciated role of muscle in health and disease. American Journal of Clinical Nutrition. 2006;84(3):475-482.
- [7] Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolism. Physiological Reviews. 2014;94(2):355-382.
Related pages
VO2 Max Testing
Measured cardiorespiratory fitness with training zones set from your own thresholds.
Weight Management Bundle
Nutrition, exercise prescription and metabolic measurement in one reviewed programme.
Longevity Screening Packages
Four tiers combining epigenetics, gut microbiome and physical function testing.
Medically reviewed by Dr. Anthony Stanislaus, MBBS, PBM, Cert. Men's Health
Last reviewed 12 August 2026 · Next review 12 February 2027