Metabolism – Is It “Rev-able?”

Executive Summary

Tortured soul that I am, my email inbox is full of click-bait with new hints for “revving” my metabolism (example). It’s just another burden one has to endure when one has an unnatural, irrational and insatiable curiosity about human physiology. I have to give the authors props for creativity. They’re miracle workers when it comes to unearthing some new food, activity or body hack that will rev your metabolism. Nevermind that more often than not, these tips simply rehash the same old advice. But, that’s not the worst part about the concept of “metabolism revving.” The worst part is that there’s only one meaningful way to do it. This post explores metabolism and reveals that one way. Build muscle.

Metabolism – What Is It?

In its simplest terms, your metabolism is the collection of electrical, mechanical and chemical processes that occur in your body which allow you to function. Breathing, blood circulating, maintaining constant body temperature and thinking are a just a few of these processes. In the scheme of the Six Factors that Influence Your Health, your metabolism is part of your physiology. But, your metabolism is influenced by the other five factors.

Metabolism – Why Would I Want to Rev It?

People with a higher metabolism have an easier time managing their weight (unless they are trying to gain weight in which case they want to decelerate their metabolism).

Sometimes, the Big Kahuna of metabolism, the thyroid gland. slips into a hypoactive state and this reduces overall metabolism. Of course, the opposite is also possible. One could have a hyperactive thyroid and this results in, among other symptoms, a totally revved metabolism.

Anterior thyroid

In either case, hypo or hyper, forget about any revving you may want to do on your own, you need to get a doctor involved.

Why Metabolism Revving Schemes Are Stupid (Nerd Alert)

As previously stated, most people want to increase their metabolism to lose or to stop gaining weight. Here’s why that’s the wrong way to look at the problem.

All weight loss is the result of living in a calorie deficit. Calorie deficits occur when you eat fewer calories than you burn.

How To Burn Calories

There are a nearly infinite number of ways to burn calories but when you roll them all up into major categories, they are:

  • Resting Metabolic Rate (RMR) – The calories your body burns just to stay alive.  Lots of systems, organs, and individual cells in your body contribute to your total RMR but the top 3 consumers of calories are your liver, brain, and skeletal muscles.  Half of your RMR is based on the calories burned by these three.  More than two-thirds of your total calorie burn comes from your metabolic rate.
  • Thermic Effect of Feeding (TEF) – The calories your body burns in the act of digesting food and absorbing its nutrients.  The TEF represents 10-15% of total calorie burn.  There are lots of myths based on the TEF.   For example, while it is true that if you fast, it causes a drop in metabolism, what we’re really talking about is the TEF.  That’s a drop of no more than 15% that lasts only as long as you’re fasting.  NOTE: Fasting is diffeent from starving. Starving will ultimately reduce your RMR.
  • Physical Activity – Physical Activity includes the calories you burn from exercise plus any other additional activity you undertake including walking, climbing stairs, doing housework, working at you standing desk, etc.  This additional activity is sometimes called NEAT for non-exercise activity thermogenesis.
Percentage Contribution to Daily Calorie Burn

If in the interest of losing weight, you want to increase your calorie burn, these are the three areas where you can have a potential impact. Below we look at each individually.


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Resting Metabolic Rate

You have limited short-term control over your RMR.  The way to have the most long-term effect on your RMR is to gain weight.  Regardless of whether that additional weight is fat or muscle, your metabolism will go up.  More cells, higher metabolism.  However, fat cells don’t burn a lot of calories (There is an exception. Learn more here).  Most of the metabolism increase that happens when you add fat comes from the amount of additional support (wear-and-tear) the rest of your body provides to keep you alive.  Muscle tissue, however, sits at number 3 of the top 3 consumers of calories even when you’re at rest!  So replacing fat with muscle ends up being the best way to rev your metabolism.

As an aside, because tangents are how I roll, while your brain consumes 15% of your total calorie burn, there isn’t much you can do to change that.  Thinking harder doesn’t really increase how many calories the brain consumes.  Even something like sleeping doesn’t change your brain’s calorie burn.  There is interesting research to be done however about how mindfulness activities like meditation may impact the brain’s use of energy and we’ll discuss that in a future post.

Thermic Effect of Food

By definition, the more you eat, the more calories you burn through feeding’s thermic effect.  However, in most cases, you’re going to consume more calories from eating than you burn by eating.  The exception is if you increase your pure fiber consumption and while most people consuming a North American diet could benefit from eating more fiber, too much fiber can lead to unpleasant consequences for you and everyone around you.  Nope, your opportunities to increase your daily calorie burn through TEF are limited and the overall impact will be small anyway given that TEF as a whole only represents 10-15% of the total burn. So forget about those calorie burning foods you hear about. They don’t exist.

Physical Activity

This is where you have the most opportunity to impact your daily calorie burn because the amount of physical activity in your life, whether from exercise or NEAT, is mostly within your control.

The bar graph below is an example of two people who might be very similar except one is sedentary and one is active.  For the purposes of this example, I assumed their RMR is the same.  This is because, although the active person may have more calorie burning muscle, the sedentary person may weigh more and the result, for our purposes, even out.  The TEF is virtually the same and even if it is different it is such a small percentage of overall burn that it isn’t worth worrying about.  The nice thing is that even though this limits your opportunities for increasing your total calorie burn to physical activity, there are so many pleasant ways of being active, even if you don’t like to exercise.


The active person burns more calories. And if the type of activity he or she performs results in building more skeletal muscle, RMR will end up increasing too.

The Best Things to Do To Increase Calorie Burn

  1. Be active.
  2. Get into the habit of doing resistance exercise to build muscle.
  3. Eat Protein in Every Meal to make sure your body has the basic materials to add muscle.
  4. Forget about hacks for quickly increasing your metabolism. There are few pleasant ways to do this. But, if you want to try here are a few:
    • Get sick
    • Break a bone
    • Increase your brown adipose tissue (and decrease your libido) by taking cold showers

If, you’re interested in pursuing a reasonable path to manage your weight or metabolism, why not contact me.

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