What to Eat (and Avoid) Before a Metabolic Testing Appointment
Resting metabolic rate (RMR) testing measures how much energy your body burns at rest. Because food, caffeine, and exercise all temporarily raise your metabolism, a little preparation makes your results far more accurate. Here is how to get ready.
Testing · 3 min read
The night before and morning of
RMR testing is usually done after an overnight fast so digestion is not inflating your numbers. Follow the specific instructions your provider gives you, but the common guidelines look like this:
Fast for about 4 or more hours before the test (often tested first thing in the morning)
Avoid caffeine the morning of, since it stimulates metabolism
Skip vigorous exercise for several hours to a day beforehand
Avoid nicotine before the test
Sip water as needed; being well hydrated is fine
Why these rules matter
The test works by measuring the oxygen you use while lying still. Anything that revs your metabolism, a workout, a coffee, or a recent meal, makes your resting number look higher than it truly is. That can throw off the calorie targets built from the result, which is the whole point of testing.
What to expect during the test
You will rest quietly, often reclined, and breathe normally into a mask or mouthpiece for roughly 10 to 20 minutes. It is painless. Wear comfortable clothing, arrive relaxed, and give yourself a few minutes to settle before it begins.
