Are We Thinking About Metabolism All Wrong?

It happens every night at bedtime: A crazy-eyed woman tries to sell me something that will “ignite” my metabolism. It’s not always the same woman, and it’s not always the same incendiary verb. The variations are endless. Some would like to torch it, others want to make “my burn” work “smarter,” and a whole host of folks are promising to optimize, boost, supercharge, support, and reset my metabolic engines. No matter how they word it, or what miracle they are goading me to spend my time and money on to fix it — sunlight! Protein! Green tea! Kettle bells! Creatine powder! Berberine gummies! — the people who live in my iPhone all seem to agree on one thing: My metabolism is not all right.

I don’t even want to tell you what the cross section of my withered midlife thigh muscle is going to look like if I don’t get a handle on this thing ASAP. (Thank you for that mental image, @dr.longevity.)

My first thought, when one influencer after another started to home in on all things metabolism was “Isn’t this a little retro?” As a survivor of multiple waves of diet culture who undertook her first weight loss plan at age 11, I’m not new to fearmongering, and I’m certainly not new to the word metabolism. You might as well tell me that “calorie counting” is a hot new science. Research into the concept began in the 19th century. By the time my mother came of age in the 1970s, the notion that some people were blessed with a “fast metabolism” while others were cursed with slower systems was the going explanation for why some people were skinny and others were not. By the Jane Fonda era, “boosting your metabolism” was the main reason to shimmy into a leotard.

Why is it the subject of so much chatter now? That’s due in part to the rise of GLP-1 medications, which have arguably ushered in a new, post-body-positivity era of unabashed weight-loss enthusiasm — one that has corrected some old misconceptions about the metabolism while (presto!) giving rise to a whole new set of them.

The search term metabolic health shot up 130% on Google within the last year.

For instance, most of us still tend to use the word “metabolism” to refer to the rate at which the body breaks down food and turns it into energy, and how much overall energy — or, if we’re being honest here, calories — we burn. Technically, though, that’s just a slice of the pie. Your metabolism comprises all of the chemical processes going on in your body: heart pumping, brain thinking, muscles firing. “Think of the inside of a factory — let’s say they’re filling Coca-Cola bottles,” says Ashley Koff, RD, author of the new GLP-1 how-to tome Your Best Shot. “It’s all the machines that are working and everything that’s happening.”

That complex internal factory is what we’re talking about when we hop onto the even hotter — and more politically loaded — topic of metabolic health (a search term that shot up 130% on Google within the last year). Your “metabolic health” could be considered a measurement of how well your factory is running. It’s also quickly become a convenient matryoska-doll-like container for all of the wellness topics we’ve obsessed over in recent years, from protein grams to strength training to blood sugar monitoring. Viewed from a certain angle, it’s like all of “wellness” is being swallowed up by metabolism.

Which, again, is sort of new, and also sort of not. Metabolic syndrome as a medical diagnosis has been around since the ’50s; it applies to patients who have multiple risk factors at once (some combination of high blood sugar, high blood pressure, unhealthy cholesterol levels, and excess abdominal fat) that increase their risk for heart disease, diabetes, and stroke. The concept of metabolic health — as a wellness goal we should all aim for, rather than a diagnosis to be treated after the fact — entered the chat very recently. The major catalyst was a landmark study published in the journal Metabolic Syndrome and Related Disorders in 2019, which found that a dismal 12.2% of American adults are metabolically healthy, meaning they have healthy levels of the aforementioned markers and they don’t need medication to keep it that way.

Longevity bros like Andrew Huberman; Dr. Mark Hyman (author of Ultrametabolism), M.D.; and the recently disgraced Peter Attia describe poor metabolic health as the great health crisis of our time — and preach that improved metabolic health, for those with the resources and the stick-to-it-iveness to achieve it, is the gateway to a longer, better life. Dr. Casey Means, M.D., whose confirmations hearings for Surgeon General made headlines in late February, is MAHA’s queen of all things metabolic. She rose to fame on a 2024 bestseller co-written with her brother, Calley, titled Good Energy: The Surprising Connection Between Metabolism and Limitless Health. The book argues that the full menu of human misery — depression, anxiety, infertility, insomnia, heart disease, erectile dysfunction, type 2 diabetes, Alzheimer’s, dementia, cancer — has one root cause. You guessed it: poor metabolic health. Means's critics point out that she has skin in the metabolic game in more way than one — she may not be a licensed physician but she is a co-founder of Levels Health, which uses continuous glucose monitors (CGMs) to provide real-time biofeedback

Flipping literally decades of diet think on its head, obesity specialist and endocrinologist Dr. Spencer Nadolsky says the speed of your metabolism generally doesn’t correlate to the number on the scale.

Among a certain data-forward cohort, this kind of apocalyptic thinking has birthed a new class of metabolic obsessives. The booming unregulated peptide market you’ve no doubt been hearing about includes a host of injections said to be “metabolic regulators.” The newest buzzword is metabolomics, an emerging field that promises to decode your “unique metabolic signature” so that everything you eat and do is custom built for your personal biochemistry.

Biohacker Dave Asprey, who does not have diabetes, leads the charge in this kind of thinking. He eats a diabetic diet (high protein and fiber, low sugar and carbs) and sports a continuous blood glucose monitor to show how everything he consumes impacts his blood sugar, and thereby his metabolic health. In January, the annual tech show CES in Las Vegas saw the debut of Isaac by PreEvnt, the first blood glucose monitor that doesn’t break the skin. A miracle for diabetics who need it — and hackers who may not.

As for the “igniting” effect that all of Instagram Reels would like to offer me… That sounds like a health benefit, right? But the more I began to dig into it, the more it seemed like calorie-counting by a different name. (In this case, you’re counting what you’re burning as opposed to what you’re consuming.) Koff said as much in an aside: “By the way, nobody really wants a faster metabolism — the end result is people want to lose fat. That’s what we’re talking about here.”

Flipping literally decades of diet think on its head, obesity specialist and endocrinologist Dr. Spencer Nadolsky, D.O., the CEO of virtual health clinic Vineyard, says the speed of your metabolism generally doesn’t correlate to the number on the scale — something scientists have known for decades that still hasn’t quite made its way down to much of the general populace. “The big myth is that people who struggle with their weight have a slow metabolism,” he says. “For ages, we believed that smaller bodies were that way because they had faster metabolisms. The truth is bigger bodies have a higher metabolism, because they have more tissue.” More tissue, more chemical processes in the body.

That’s not to say that our metabolism doesn’t matter, and that there aren’t things we can do to make it run a little faster. Dr. Marika Holte, M.D., associate medical director of the online medical platform PlushCare, says when her patients ask her what they can do about it, she starts by explaining the basics: Their bodies use energy four primary ways. Some of these can be dialed up. Others can’t.

We burn the bulk of our energy — by some estimates as much as 70% — simply by existing. All the things that keep happening even when you’re not moving add up to your basal metabolic rate, sometimes referred to as your “resting rate” or RMR. That’s set by several big things you can’t control — age, sex, genetics — and a couple that you (kind of) can: body size and composition.

Some 15% of your energy is spent on “NEAT” or non-exercise activity thermogenesis. Think: housework, gardening, standing, and even fidgeting. “That’s all of the activity you do without thinking about it,” says Holte. “I like to talk with my hands, right? So I am moving all the time and thus burning energy.”

Another 10% of our overall energy goes to digestion. Different foods require more energy to digest. The protein that metabolism influencers can’t get enough of requires the most energy to digest and helps you build more muscle. Win-win.

At the very bottom of the list: intentional exercise, which accounts for about 5% of all energy use. Exercise, of course, burns energy directly, but if it includes rigorous strength training, it may also help build more muscle, which in turn contributes to your resting metabolic rate — because muscles use more energy than fat, even at rest.

It takes a hell of a lot of work to pack on 10 pounds of muscle. I’m supposed to do all of that so that my resting metabolism can burn the equivalent of one extra cup of popcorn (no butter) per day?

This is a popular idea on the Internet right now: The higher your muscle mass, the more energy you use, around the clock. But Nadolsky cautions that while muscle-building can improve your resting metabolic rate, the improvement is relatively modest. Body fat burns 2 to 3 calories per pound, per day, while lean tissue (which includes muscle) burns 6 to 10 calories per pound, per day. This means that even if you put on 10 pounds of pure muscle, at most you will burn 60 to 100 more calories a day at rest.

Reader, it takes a hell of a lot of work to pack on 10 pounds of muscle. I’m supposed to do all of that so that my resting metabolism can burn the equivalent of one extra cup of popcorn (no butter) per day? “It’s not nothing,” Nadolsky says. But it’s not the transformational “torching” that’s widely imagined online.

When I tell Nadolsky that, once again, I feel duped by my feed, he doesn’t disagree. But he suggests I may be missing the point. “Who cares about what your muscles do at rest?” he says. “The real benefit is that when [you] have more muscle, you’re going to be able to do more, and that’s where you’re going to be able to burn more calories. It’s a force multiplier.”

As for the pills, the powders, the gummies, the tablets? You had to see this one coming. “Buyer beware,” says Koff, of so-called metabolism boosters, which are unregulated by the FDA and tend to have little to no data to support their claims. She points out that in a system that includes all of your bodily machinations, taking a supplement that might amp up one small aspect of your burn is unlikely to produce a result you’d actually see.

Holte says the most well-documented metabolism-boosting supplement is probably green-tea extract. Popping it three times a day could help you burn about 100 extra calories — when you need a deficit of 500 calories a day to lose 1 pound a week. Whether this investment strikes you as completely worth it or a waste of time and money is a pretty good litmus test of how metabo-obsessed you already are. For Holte, it falls into the latter category: “Spend your money on exercise,” she advises.

Other good ideas for your metabolism — and your life: move more, eat breakfast and don’t skip meals, sleep, drink plenty of water to keep your system moving. And, when you start your nightly scroll tonight, remember this: No matter how many crazy-eyed women insist you need their help because your metabolism grinds to a halt in your 30s and 40s — that’s another widely ’Grammed “fact” that’s just not true. What slows down is you. That desk job? Not so hot for your metabolism.