Aging is natural. As you’ve noticed, we all do it. And, as you’ve also probably noticed, we all seem to do it at different rates. For instance, one friend might pass for a decade younger and another, well, let’s just say, may present somewhat older than their chronological age. So what’s going on? Sure, genetics plays a role but to a large degree, as the research of the past decade has made plain, the aging process is driven by metabolism. It’s a concept that connects a lot of dots. What do I mean by “metabolism”? As I’ll explain in a minute, it boils down to energy – how we consume it in the form of food, how we turn it into fuel inside our cells, how we burn it and how we store it. When our metabolism is working the way nature intended it to, we’re on track to live hale and hearty lives into our 80s and maybe beyond. When it’s not, metabolism becomes the driver –often the main one – behind the classic “diseases of aging” (think, type 2 diabetes, heart disease, dementia, kidney disease, even cancer) – that rob so many of us of good years and decades, over the second half of our lives. Here’s a topline on what’s going on with your metabolism – and how you can make it your ally in your good health journey: 

Metabolism and energy efficiency.

Our bodies take the calories we consume in food and converts that into the energy our bodies need. But whether that process supports our long-term good health or undermines it depends on how efficiently we burn that energy. If we don’t overwhelm the system with more calories than we need (I’m talking sugary, low fiber, “energy-dense” foods) and we burn the calories we do take in by firing our muscles in physical activity – then we’re running a lean, clean machine. 

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But, if we do the opposite, then the pancreas has to produce a lot of the hormone insulin to clear all that sugar from the bloodstream and get it into our cells. And those cells get less good at burning that sugar as fuel and more prone to storing it as fat, some of which infiltrates our organs and muscles, fouling up our body’s machinery with a layer of sludge. Plus, over time, our cells grow less and less sensitive to the constant infusion of insulin – they become ‘insulin resistant.’ 

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The first stop on this unhappy metabolic trip is prediabetes – the pancreas has to pump out even more insulin – and the last stop is type 2 diabetes – the pancreas starts to run out of gas, and insulin, and the sugar circulating in our blood starts ratchets up to toxic levels. There’s a reason doctors sometimes call type 2 diabetes a form of “accelerated aging.” For all the harm it causes directly, it injures, and kills, more people by increasing the likelihood of developing heart disease, kidney disease and dementia. (Doctors sometimes refers to Alzheimer’s as “Type 3 diabetes.”)

‘Metabolic Syndrome’ – the early warning system.

A metabolism that’s headed downhill is very often a stealth assassin – the erosion develops slowly, steadily, invisibly – until the doctor hits you with a shocking diagnosis like type 2 diabetes or atherosclerosis. But we do have an early warning system which we call metabolic syndrome. It’s defined by a constellation of borderline numbers on some or all of a bunch standard health measures. (Hopefully though, you’ll decide to take control of your health before these sub-par measurements start to surface!) 

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Considering that by some estimates one-third of adult America qualifies as having this syndrome, clearly, there’s a lot of warning going on and not much (or certainly nowhere near enough) attention being paid. But what do the sub-par number look like? In general, the usual rule of thumb is: a waistline for women of 35 inches or greater or 40 inches or greater for men; fasting glucose 100 mg/DL or above; HDL cholesterol less than 50 mg/dl for women, 40 mg/dl for men; triglycerides above 150 mg/DL; blood pressure above 130/80. You’ve been warned.  

Metabolism and energy production.

When glucose (blood sugar) and fatty acids do enter the cells to be burned for energy, the metabolic drama doesn’t stop. The “power plants” of the cells – the mitochondria – handle the combustion. But as we push into our middle and senior years, the number and size of those mitochondria drop, in other words our metabolic “engines” become smaller and less efficient. 

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Some of this process is inevitable, but the good news is that you can push back by staying physically active. Any kind of movement will healthfully stress the mitochondria, but regular doses of cardio and strength-building resistance exercise will give it the biggest boost.  This form of healthy stress also promotes the dismantling of old and tired mitochondria before they turn toxic, for instance, when they experience dangerous mutations. There’s also evidence that supplements that pump up some of the ‘co-factors’ in the energy assembly line can provide an energy boost, for instance NAD+. But basic B vitamins like B3 and B12 are fine as well. 

Metabolism – and energy budgeting.

Metabolism isn’t just about burning energy (so-called ‘catabolic’ metabolism). It also covers the process of building new tissues from the proteins we take in as food (so-called ‘anabolic’ metabolism). Think of this burning/building balance as your energy ‘budget.’ When you’re young and growing, you want the calories you eat to make you bigger and stronger. But when we hit middle age, we want less growth – and the toxic metabolic byproducts that come with it – and more energy invested in cell maintenance and repair, the winning strategy for the long game. 

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Our mTOR system is the chief regulator here, and as we age, we want to “inhibit” mTOR, so that instead of continually creating a bunch of new cells (all too often, fat cells), we prompt the body to recycle parts from old cells to make new ones – “autophagy” is the technical term –  so they don’t grow sluggish or “senescent”. That way our bodies carry out the millions of tasks they must discharge with renewed efficiency and robustness. 

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To help the aging body stay on budget, you can’t do better than getting plenty of physical activity and keeping a lid on calories. Getting the day’s calories during a compressed time window, say 8-12 hours, by following a time-restricted eating or intermittent fasting regimen may provide an extra budget-balancing nudge.

The stress/sleep connection.

Taking care of your metabolism is not just a physical proposition. What goes on in your head can counts for just as much. What happens when stress gets the better of us? It stimulates the overproduction of our primary stress (and energy) hormone cortisol which in turn promotes insulin resistance and all the metabolic ills we’ve already described. And poor sleep and too much stress are so intertwined, it’s often impossible to say where one ends and the other begins. Stress encourages lousy sleep habits and insufficient and/or lousy sleep pumps up stress, and those high cortisol levels. 

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And what do, for hormonal reasons, under-slept and stressed-out people tend to crave? Sugary “energy-dense” comfort foods. Call it a vicious circle or a downward spiral, it’s not good, and, if you want to enjoy your senior years, it’s up to you to hit the breaks without delay. You probably know the drill: abide by a regular sleep schedule, cut out the booze, make time for exercise and lean into de-stressing mindful activities like yoga, meditation, hanging out in nature, a hot bath before bed – you name it. Good sleep keeps your metabolism running efficiently by balancing hormones (including cortisol), improving insulin response, and supporting recovery, whereas poor sleep can lead to metabolic dysfunction, weight gain, and increased disease risk.

Inflammation – when a good metabolism goes bad.

As we’ve described, there are a number of ways a metabolism can go off the rails – and send you on the aging express train. But no matter what the cause, an angry metabolism will usually do its damage with one weapon of choice – inflammation. That plays out at the cellular level, when oxidative stress (think free radicals) drive harmful mutations. Or it happens at the organ level, when the vessels that carry blood to and from our heart and brains become inflamed and more prone to developing lethal cholesterol plaques. Or it may be a visible process, when an inflamed metabolism encourages the deposition of fat, especially the visceral fat that builds up around the organs in the midsection, dragging down function and spitting out inflammatory molecules – cytokines – which travel the bloodstream, wreaking havoc wherever they reach. If the inflammation villain is familiar, so are the healthy habit heroes we call on to defeat it – a healthy diet with proteins from clean sources, plus lots of colorful veggies (go easy on the starchy ones) and low sugar berries; plenty of physical activity; good sleep habits; and ready access to practices that reliably keep stress from getting out of hand. 

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‍BOTTOM LINE: Metabolism plays a big role in how we age and how long we live. It’s involved in everything from how we process energy and fats to how our mitochondria work and how our cells respond to nutrients through pathways like mTOR. Consequently, it’s essential that we mind our metabolism – and do our best to keep it on an even keel. Much of that we can do not only by keeping an eye on the numbers, but also by implementing the kinds of good-for-you daily habits that support good metabolic function, which in turn set the stage for healthy, vibrant aging.