APEX PWR  |  Nutrition Nook

RMR Test Portland, Oregon: The Accurate Way to Find Out Your BMR

There is a video circulating on social media that captures something worth paying attention to. A woman in a car, visibly furious, reacting to another influencer who is calmly displaying "what 800 calories of clean food looks like." Sashimi, two cans of tuna, avocado, peach, arugula, cucumber, tomato. Beautiful. Photogenic. Marketed as proof that under-eating is not actually under-eating, as long as the food is whole and pretty.

The reaction in the car gets to the truth. 800 calories of clean food is still 800 calories. Calories are literal units of energy, the fuel that keeps you alive, pumping blood, breathing oxygen, regulating temperature, keeping your organs online. Quality oil does not run a car on an empty gas tank. Micronutrient density is not a substitute for energy.

This is the conversation we have at APEX PWR with new clients more often than any other. Especially with women, especially with women who came in wanting to "eat healthier" and lose weight, and especially with women who have been quietly eating somewhere between 800 and 1,200 calories per day for months or years and wondering why they are tired, why their bones ache, why their hair is thinning, and why the scale has stopped moving.

This article is the wake-up. Here is what your BMR actually is, what eating below it actually does, and how to find out your real number so you can stop guessing.

What BMR Actually Is

Your basal metabolic rate (BMR) is the number of calories your body burns at complete rest, doing nothing but staying alive. Pumping blood. Breathing. Maintaining body temperature. Running your brain, kidneys, liver, immune system, and every other organ. It is the floor.

The average adult BMR sits around 1,400 calories per day. People with more lean muscle mass tend to fall higher. People with less muscle, or smaller body sizes, tend to fall lower. But that 1,400 calorie figure is a useful baseline for most adults to anchor against.

Resting metabolic rate (RMR) is a very close cousin to BMR, measured under slightly less strict conditions, and is what is performed in clinical and commercial settings. The two terms are used interchangeably in practical nutrition. When someone says "RMR test," they mean the test that measures your real metabolic floor.

That floor matters because it defines the line. Eat above it, with intelligent structure, and your body has the energy to function, build, recover, and lose fat sustainably. Eat below it, day after day, and your body starts making compromises. Bone tissue, muscle tissue, hormonal output, and organ function become bargaining chips.

What Chronic Under-Eating Actually Does

The research on chronic low energy availability, especially in women, has matured significantly in the last fifteen years. The International Olympic Committee's consensus statement on Relative Energy Deficiency in Sport (REDs), first published in 2014 and most recently updated in 2023, catalogues what happens to the human body when energy intake stays below the floor it needs.

Five consequences are well-documented and worth understanding.

Why This Hits Women Hardest

The wellness culture aimed at women has spent two decades celebrating thinness as health, and the data on what that has produced is now visible in clinical settings. Eating disorders aside, the bigger population issue is the much larger group of women operating in subclinical chronic under-eating. Not low enough to trigger a diagnosis. Low enough to slowly erode the systems that keep them strong.

Bone density is the most damaging long-term consequence. Women lose bone density naturally through perimenopause and menopause, with the steepest decline in the years immediately following the final menstrual period. Entering that window with a deficit, from a decade of under-eating in your thirties and forties, accelerates the trajectory toward osteoporosis. Many women find out only when they break a bone in their sixties.

This is why the framing matters. You can be thin and bone-fragile. You can have a "good" body fat percentage on a scale and still be losing the structural tissue that keeps you upright and unbroken. Body weight alone is a poor measure of health. Body composition, bone density, and metabolic rate paint the actual picture.

Chase Strong, Not Skinny

The reframe is straightforward. The goal is not a smaller number on a scale. The goal is a stronger, more muscular, more durable body with healthy bone density, intact hormonal function, and a metabolic rate that supports a full life. That body is built by eating enough, training with intent, and measuring the things that actually matter.

At APEX PWR, three measurements anchor the picture:

• DEXA Body Composition Scan: precise measurement of fat mass, lean mass, and where each is distributed across your body. The clearest answer to the question "is this body actually changing the way I want it to."
• DEXA Bone Density Scan: the same Gold Standard imaging used in clinical medicine to assess osteopenia and osteoporosis risk. Critical for women starting in their 30s to catch negative trends early, especially during perimenopause.
• RMR Test: your real metabolic floor, measured directly. The number every nutrition decision should be calibrated against.

All three can be completed in a single appointment.

How to Figure Out Your BMR Accurately

There are two paths to a BMR number. One is fast and free and an estimate. The other is the actual measurement.

Online Calculators: Estimates, Not Measurements

The most common BMR calculators use predictive equations like Mifflin-St Jeor or Harris-Benedict. They estimate your BMR based on inputs you provide: age, sex, height, weight. They are useful as a starting point, but they have known accuracy limitations. Frankenfield, Roth-Yousey, and Compher's 2005 systematic review in the Journal of the American Dietetic Association evaluated multiple predictive equations against measured RMR and found that the most accurate equation (Mifflin-St Jeor) still produced individual errors of 200 to 500 calories or more in roughly 20 to 30 percent of cases.

That margin matters. A 300-calorie overestimate means you may eat in a deficit that is much steeper than you think, slipping below your real BMR for months without knowing. A 300-calorie underestimate means you may eat more than necessary while expecting fat loss results that never come.

RMR Testing: The Accurate Way

An RMR test directly measures the calories your body is actually burning at rest. It does this through indirect calorimetry, which is a non-invasive analysis of the gases you exhale. You breathe normally through a mask for about 15 minutes. The machine measures your oxygen consumption and carbon dioxide production. From those values, your real metabolic rate is calculated to a precise number.

This is the test used in metabolic research, clinical nutrition, and high-performance athletic settings. It is the Gold Standard for finding out what your body actually needs.

What to Do With Your Number

Knowing your RMR is the starting point, not the ending. The number tells you the floor. What sits on top of that floor (your activity level, your training, your goals) determines your actual daily caloric needs.

This is where structured nutrition coaching matters. The nutrition coaching practice at APEX PWR is led by Jennie Carolan, MS, who holds a Master of Science in Food Science and Nutrition. Her coaching framework centers on a deceptively simple principle: eat as much as possible while still progressing toward fat loss and body composition goals. The point is sustainable progress at a pace your body can support, not the steepest possible deficit your spreadsheet allows.

That approach protects metabolic rate, preserves lean muscle, defends bone density, and creates the kind of food awareness that lasts beyond a 12-week phase.

For most clients, the path looks like this:

• One-Time Macro Breakdown: a single session with a coach to translate your RMR result into specific daily targets for protein, carbohydrates, and fats. For people who want the number and prefer to execute on their own.
• 12-Week Nutrition Challenge: a structured group program for sustained behavior change with regular check-ins and accountability.
• VIP 1-on-1 Nutrition Coaching: ongoing individualized work with Jennie for clients with more complex goals or a longer-term commitment.

One Appointment. Three Tests. A Full Picture.

For clients who want the complete metabolic and body composition baseline in a single visit, the RMR Test, DEXA Body Composition Scan, and DEXA Bone Density Scan can all be performed in one appointment at APEX PWR in Tigard, Oregon.

What you walk out with:

• Your exact resting metabolic rate, measured by indirect calorimetry
• A precise body composition breakdown: total fat mass, lean mass, regional distribution, visceral adipose tissue
• A bone mineral density baseline (T-score and Z-score) to benchmark against future scans
• Same-day results, same-day conversation about what the numbers mean

The RMR test alone is $167 and takes about 15 minutes. Add the DEXA scans and you have a complete picture of your metabolic and structural health in roughly an hour.

Frequently Asked Questions