Does My Metabolism Really Slow Down By 90 Percent When I Sit Down?

One of my most memorable conversations as a Bally Total Fitness employee occurred when a middle-aged female club member who was usually quite friendly descended upon the front desk of the club, her face awash with a mixture of sweat and frustration. “I don’t see the point of it all!” she wailed.

“The point of what?” I asked, while taking a swig from my silver can of Bally Blast energy drink.

“Cardio,” she answered. “I just walked for half an hour and I only burned 150 calories; you’re probably drinking more than that right now!”

I spun the can around and inspected its nutritional contents. “This has 120 calories,” I corrected her, honestly not intending to sound sarcastic.

“That’s not the point!” she snapped. “It’s so easy to put calories back on that cardio doesn’t do anything! And how many calories are in a pound of fat?”

“About 3,500,” I answered.

“So I’d need to do this every day for a month just to lose a pound!” moaned the woman.

“You’re not factoring in your basal metabolic rate,” responded Chris, one of the star trainers of the executive club who had wandered over to rescue me. “You burn the majority of your calories when you’re at rest. Your body is always burning calories.”

At that point, Chris escorted the lady into the personal training office to help her calculate her body fat percentage — along with the calories she burned at rest — with some technological aid provided by one of those handheld body-fat percentage calculators. It was also at this point when I fully understood how little most people understood about their individual metabolisms, and how few calories most people burn during cardiovascular training in comparison to the number of calories they burn simply by existing.

How do I figure out what my basal metabolic rate is?

The formulas for calculating the BMRs of men and women differ, but they both involve a healthy amount of mathematical acumen to compute. The present accepted formula for calculating a man’s metabolic rate — aka the Harris-Benedict Formula — is 66 + (6.23 x weight in pounds) + (12.7 x height in inches) − (6.8 x age in years). So a 20-year-old, 200-pound man standing 6-feet tall would burn approximately 2,090 calories over the course of a day simply by existing and doing nothing else of value.

I heard somewhere that the function of my metabolism can dip by 90 percent if I simply sit down. Is that true?

This understanding is the result of a quote from Annabelle Santos Volgman, the medical director of the Rush Heart Center for Women in Chicago. What she specifically said was, “After you sit for just 30 minutes, your metabolism slows 90 percent,” and then she addressed all of the harmful effects of this. The majority of her concerns were offshoots of how remaining motionless allows the movement of bad cholesterol to slow to a crawl until it clogs the arteries and moves into the lining of blood vessels. Obviously, this is a regrettable predicament, and it underscores the need to find opportunities to improve health through movement. 

That said, your metabolism is certainly no less active at any other point than when you sleep, and failing to accumulate sufficient hours of sleep is also harmful to your metabolism. Therefore, when it comes to optimizing your metabolism, it would appear as if you’re trapped within an unavoidable catch-22. 

Keep in mind, your basal metabolic rate already takes this into account. Your BMR is a calculation of the quantity of calories your body burns in order to perform life-sustaining functions only. So if your BMR is 2,000 calories per day, this means that your body would require 2,000 macronutrient calories to sustain itself even if you sat around chatting with babes online all day, like Kip Dynamite. However, this is an essential starting point, and it is not intended to suggest that your caloric consumption would be reduced by 90 percent if you failed to move.

So how do I use my basal metabolic rate practically?

Use your BMR as a critical piece of knowledge within a set of healthy individual dietary guidelines. If your BMR indicates that you need to ingest 2,000 calories daily in order for your body to sustain itself, and you regard your bodyweight to be unhealthy, you could use the 2,000-calorie mark as a baseline around which to plan your activity level and food consumption. Since your body is clearly burning a minimum of 2,000 calories each day, safely and responsibly anchoring your caloric consumption closely to this level is a solid strategy around which to build a consistent weight-loss plan without thoroughly starving yourself.

At the same time, remember that there’s more to your metabolism than mere weight management. You can finely-tune your diet to such an extent that you visibly maintain a healthy-looking exterior while remaining internally unhealthy. If you sidestep an obesity-related affliction only to fall victim to a cholesterol-induced heart attack, that would be analogous to being so preoccupied with avoiding a falling boulder that your attempt to dodge it sends you hurtling off a cliff.