Muscle = Metabolism

Welcome back to another week of Move to Improve! We’re covering one of my favorite topics today, so grab a glass of *insert your bev of choice here* and let’s get started!

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How many of you have heard someone say their metabolism slowed as they got older? Raise your hand if you’ve said it, yourself 🙋

It’s a very common saying and has widely become accepted as just “the way things are.” But what if I told you that you actually have much more control over this than you thought? I won’t bury the lede here:

You aren’t completely powerless to an inevitable and drastic “slowing” of your metabolism.

Let’s first define our terms. That’s always a good way to start. According to Oxford, “metabolism” is “the chemical processes that occur within a living organism in order to maintain life.”

Hmm. Not quite the definition you expected? Chemical processes? I thought we were just talking about burning calories from the food we eat. Well, we are. But the actual processes of this, from step A to Z, are incredibly complex.

A more everyday definition of “metabolism” as we commonly refer to it could be “how much energy we burn every day going about our lives.” That’s a little easier to grasp. That definition more closely aligns with an exercise science term known as “Total Daily Energy Expenditure” or TDEE. Now let me show you the components that make up our metabolism/TDEE.

Sources: ResearchGate & Cheat Day Design

Have a look at these two images. Not to get caught up in all the abbreviations, you can see that your Basal Metabolic Rate (BMR) comprises the vast majority of the Cals you burn in a day. BMR is the low and steady hum of just living and breathing and staying alive at rest.

The next biggest chunk after that typically comes from NEAT (Non-exercise activity thermogenesis). Basically just the everyday movement and activity that isn’t structured, intentional exercise (like the 2 minutes of movement every hour we talked about in my first post 👀).

TEF, or the thermic effect of food, is literally the energy it takes to digest, break down, absorb, and process the food you eat. Yes, that burns Calories. Hey, intestines gotta werk too!

Lastly, you’ll see physical activity or EAT (exercise activity thermogenesis) rounding off the rest of the calories we burn in a day. A pretty small slice for the average person. But if you burn 2,500 Calories a day and 300 Calories in your workout, that is a pretty small portion.

Are you surprised to see how much energy we burn at rest and how little we burn from exercise? Most people are. Of course these percentages vary from person to person. Someone training for a marathon is obviously going to have a higher percentage of the energy burned attributable to physical activity than someone who’s sedentary.

But it almost always holds true that our basal metabolism, followed by our non-exercise activity, constitute the majority of the Calories we burn every day.

Now, think back to the beginning. “Slowing metabolism.” Know what contributes to the majority of those two factors (80+% of what we burn every day)?

Our muscle mass.

That’s right. Our muscles are energy-burning machines. If you’ve got more muscle mass than Captain America Sally next door, even if you’re the same weight, you’re going to burn more Calories than her (and thus have a “higher/faster” metabolism) just living your day-to-day life.

The Nuance: Yes, cardiovascular exercise (cardio) burns Calories. But probably less than we think… and it’s a lot of hard work! I will never downplay the importance of aerobic exercise for health and longevity. We should grow to love it, because it's so good for us.

But if you’re trying to set yourself up to have a robust metabolism for the long-term, you’d probably be well-served to dedicate significantly more time to muscle-building activities like weight training!

When we’re young teens and 20-somethings, we’re also likely just moving around the world a lot more. Pickup ball games, speed walking 9 minute-55 second intervals across campus to class, and enjoying activities with our friends. As we age and settle into the workforce, we’re likely much more sedentary and forgo some of those active hobbies for chiller ones like knitting, reading/writing, or bingeing the latest true crime docu-series.

Most people lose somewhere between 3–8% of our muscle mass every decade starting at age 30, and this only accelerates after age 60. (This is similar to our loss of aerobic capacity with age, which we’ll discuss in the future.) Losing muscle mass is a major cause of and contributor to disease and disability as we age. There’s even a disease term for dangerously low muscle mass: sarcopenia.

Muscle is not only important for general metabolism, but is an essential tool to battle diseases such as diabetes—if our muscles are using up all the food we eat, they don’t get a chance to wreak the havoc they might otherwise cause in a sedentary body!

So with age, most people experience both a decrease in energy burned through physical activity, and a decrease in muscle mass, which is that baseline for our metabolism. We’re lowering the floor of daily Calories burned when we lose muscle mass. 

That’s one reason why many people struggle on heavily restrictive diets. They cut Calories sharply and keep losing muscle mass, requiring fewer and fewer Calories just to keep from gaining weight.

Food. Is. Fuel. Our muscles use that fuel better than anything else we’ve got. Why not fuel them appropriately (also more on that in future issues) and use them!

This isn’t a completely inevitable decline. Building more muscle increases our metabolism. Simple as that.

Spend more time with the weights. No matter how old you are, you can still build muscle! If you’re new to it, start small. The biggest improvements in fitness are always when someone goes from nothing to anything. So do anything. And reach out to me if you have questions about how to get started!

You can significantly and meaningfully slow—and even reverse—the loss of muscle as you age. There’s plenty of time, and there’s no better time to start than now.

That’ll show the youngins 😉

✅ Take Action

Every newsletter's Take Action section will invite you to take small steps to improve your health. Recognizing that we all have different capabilities, I'll offer three different levels of action you can choose to take.

Level 1: First, stop starving yourself trying to lose weight and tanking your metabolism. Then, pick up a weight—even a soup can—and move it. Climb a flight of stairs a few times. Use those muscles in everyday activities!

Level 2: Lift weights or do bodyweight strength training at least twice per week! Make sure you’re supervised if you’re new at this and consult with appropriate professionals, but your body will thank you for the muscle you build.

Level 3: Already exercising quite a bit? If you’re doing way more cardio at the moment, let me encourage you to shift a training session or two to muscle building. Don’t worry about heavy weights. Use slow, controlled contractions through a full range of motion to put on maximum muscle and feel that burn, baby!

This newsletter is brought to you by… me! Interested in becoming a sponsor? Know someone else who might be? I’d love to get to know you and/or your business and see how we can partner together. Reply to this email!

✍️ Drew's Picks:

• Doctors like Dr. Lyon are on the forefront of the field of "muscle-centric medicine." Check out her content if you'd like to learn more about how our muscle impacts virtually every aspect of our health!

• "Exercise, VO2 max, and longevity," part of Dr. Peter Attia's "The Drive" pocast. His podcasts are pretty scientific, but don't let that scare you off. This episode is full of golden nuggets for improving our bodies and life spans through exercise.

That's a (chicken caesar) wrap for this week! If you learned something or benefitted from this content in anyway, please share it with friends and family so we can continue to grow this MTI community 💙

Keep moving,

Drew

The content in Move to Improve is meant to be informative in nature, but it should not be taken as medical advice. It is always a good idea to consult with a trusted health professional before making any major lifestyle changes that could have a significant impact on your health. This is not a medical resource, and any opinions and articles are not intended for use as diagnosis, prevention, and/or treatment of health problems. They are not substitutes for consulting a qualified medical professional. Please think critically and take what I say with a grain of salt (aka don’t sue me).