Improving your metabolism isn’t as complicated as you think.
People make a lot of assumptions — and read a lot of clickbait articles — about metabolism and metabolic rate. “It slows down in your 30s.” “You can't change your metabolic rate.” “You can change your metabolic rate.” “Your resting metabolic rate is what actually matters.” “Don’t forget about NEAT.”
It's understandably impossible to keep it all straight.
As a personal trainer, I can’t tell you how many times I’ve heard a client say, “My metabolism is slow.” My answer to that is always two-fold. First: “How do you know?” (you probably don’t for sure) and second, “You have (some) control to change it.”
But before getting into how to improve one’s metabolism, let’s talk about what metabolism is in the first place.
Your entire metabolism is determined by four major components:
• Your resting metabolic rate (RMR): This is the amount of energy your body expends to function at rest. RMR is the most significant contributor to total metabolism, and it’s mainly dependent on the size of the person. Since muscle mass is an organ, people with more muscle mass will have more “organ” contribution to their RMR. Larger humans, even people who don’t work out, tend to have more lean muscle mass, so they get larger contributions here. And while you can make changes to your RMR on a long-term time horizon (like by changing your body composition), for the most part, your height, weight, age, and sex play the most significant role in determining your RMR.
• The thermic effect of food: You burn calories just to digest food. This contributes to your metabolism, albeit a small amount.
• Your activity level: How much you exercise, walk around, commute, and generally move throughout the day all impact your metabolism. This can look like structured exercise — such as taking a Tabata class at Equinox — or unstructured exercise, like walking to lunch. Of course, this component varies by the individual. A marathoner will have an enormous activity level contribution to their overall metabolism, whereas someone sedentary who sits at work will have a minimal contribution.
• Your non-exercise activity thermogenesis (NEAT): Your random, small, fidgety movements throughout the day (e.g., sitting at your desk and bouncing your heels up and down as you answer emails) impact your metabolism. Some people (including yours truly) fidget a lot while others don’t much at all.
The good news: Enough is known about metabolism to help people narrow in on strategies that can help them achieve their goals.
How to Improve Metabolic Rate
Activity level is the quickest fix. Short-term, structured exercises, like workouts at the Club, weekly runs, and daily bike rides, are intentional ways you can improve your metabolic rate acutely. Likewise, just walking more and spending less time sitting throughout the day can improve your metabolic rate.
Improving your metabolic rate long-term, however, calls for exercise, diet, and sleep strategies that build muscle mass and burn fat to improve your overall body composition.
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People with more lean muscle mass will have larger resting metabolic rates (though that doesn’t mean they’re necessarily lean people — it’s just a term to reference muscle mass). A 250-pound guy who works out frequently will likely have enormous amounts of lean mass on his body; because this 250-pound person is active, strong, but also just large in general, his RMR will just naturally be bigger.
Let’s say I’m 150 pounds, but I’m 25 percent body fat. I’m small but also not very muscular, so my metabolism will be much slower than someone of equal activity level who is 150 pounds but 10 percent body fat. In this scenario, we are the same size but have different body compositions.
So, yes, building muscle mass while reducing body fat can positively affect your metabolic rate, including your RMR.
You’ve also likely heard that your metabolism naturally slows with age (though this 2021 study found new evidence to contradict that belief) and that this can especially affect women, particularly through menopause. Whether or not certain components that make up your metabolism slow with age, there’s one area you do have lifelong control over: your activity level. Since you can always manipulate this variable, you can affect whether your metabolism slows down — or not — with age. Muscle mass plays a key role here, too.
With the aging process, people slowly lose their type II (aka fast-twitch) muscle fibers. These muscle fiber types are responsible for power, strength, speed, jumping, and more. Without a structured training regimen as you age, you may lose your ability to work out at a high level. That’s why it’s important to commit to a lifelong mission of staying active rather than waiting until later in life — when those muscle fibers have naturally atrophied — to make positive changes.
RELATED: How to Train Fast-Twitch Muscle Fibers
One way to offset this natural decline is to prioritize both building and maintaining lean muscle mass at every age. The more lean muscle you have at 30, 40, 50, or 60 years old, the more you’ll have left at 70 and 80, provided you stick to a strategic routine over the decades.
Ultimately, your metabolic rate is fun to understand but it shouldn’t change how you should exercise and live. People who work out, prioritize maintaining or building lean mass, eat balanced diets, and keep their energy levels high with proper sleep and exercise will have better metabolisms. It’s a tale as old as time — but it’s cliché for a reason.
Michael Crandall is a Tier X trainer at E by Equinox - Hudson Yards, where he enjoys working with his clients to fundamentally change their lives. He has worked for Equinox for the past decade, has a bachelor’s degree in exercise physiology and certifications from Precision Nutrition, is a certified strength and conditioning specialist, and is currently pursuing his license in massage therapy.