Anabolic Resistance
There’s a story we all like to tell ourselves as we age. It goes something like this:
“I’m losing strength because I’m getting older. That’s just what happens”
It’s comforting, in a way. Age therefore becomes the villain. We remain blameless. But that story we tell ourselves, whilst familiar, is also incomplete.
Because for most of us, the loss of strength, muscle mass, and confidence with our own physical self that we attribute to aging, are driven far less than the number of candles on our birthday cake, than they are by something much simpler: We stopped using the machinery that keeps these factors sustained.
What is Anabolic Resistance?
When you eat protein, your body breaks it down into amino acids. One of those amino acids — leucine — acts like an internal signal. It tells your muscles that it’s time to build, repair, and grow new tissue.
That signalling leads to muscle protein synthesis, the process that your body uses to maintain and build muscle tissue.
Anabolic resistance is what happens when your muscles stop listening to that signal. You consume protein, but your muscle tissues doesn't actively respond to that signal as well anymore. You’re not building or maintaining muscle mass as effectively as you used to.
Here’s the bit to consider: We often talk about this as “age-related decline,” as if you reach your 40th, 50th, or 60th birthday and some biochemical dial is gradually being turned down, and it’s just a race to the bottom from here on out. But there’s an uncomfortable truth that needs to be acknowledged:
Much of what we call “ageing” is actually inactivity.
There’s an incredibly simple, but brutal, study by Holwerda et al., (2024) in the journal of Medicine & Science in Sport & Exercise that helps to illustrate the point.
Researchers took healthy young adults and put one of their legs into a cast for one week. That leg was functionally immobilised for the sake of the study. The other leg stayed active and was prescribed a basic exercise regime (some simple leg extensions and curls) alongside normal day-to-day activity.
After the period of immobilisation, they measured how responsive each leg was to protein signalling. The active leg behaved as expected. Protein consumed, muscles respond, muscle protein synthesis kicks in.
The immobilised leg however showed a much weaker response with significant blunting of protein synthesis. In other words: the inactive leg showed anabolic resistance. In a young, healthy person.
Sit still or remain immobile for long enough and your body starts behaving as if it was far older, even if you’re 25…
Now flip that logic.
If a young person becomes metabolically “older” through inactivity, then an older person should be able to behave metabolically “younger” by staying active.
Protein Alone Isn’t Enough
There’s also another layer to consider. As we get older, the body generally becomes less sensitive to protein intake. Give a 25-year old and a 70-year old the exact same protein meal, and the 25-year-old’s muscles may produce approximately double the amount of muscle protein synthesis.
To get the same signal, the older adult needs to consume a much larger protein dose for the same output. This is what individuals within the health and fitness space commonly mean when they say that older adults need “more protein”. It’s just physiology.
But here’s where people can often run into trouble. They assume: “I’ll just eat more protein and I’ll be fine.” Whilst increasing protein consumption in general is an honourable goal, we’re missing a piece of the puzzle. Anabolic resistance isn’t just about protein intake. It’s about whether your body is still being asked to do the work.
If you’re not moving, not resistance training, not applying load to muscle tissue, you’re essentially telling the body, “We don’t need to hold on to this tissue anymore.”
And unsurprisingly the body listens…
So we’re left with: lower protein intake than you think, decreased sensitivity to the protein that you do eat, very little mechanical stimulus (daily activity, resistance, loading) to signal the need to muscle tissue maintenance, or growth.
That combination — low protein, low activity, low stimulus — is going to quietly strip muscle mass away over time. Year after year. Decade after decade.
Then one day, you go to stand up from a chair and it’s far harder than it used to be.
Whilst it’s really easy to attribute it to “getting old”, what we’re actively seeing is compounding neglect.
Muscle Loss Isn’t Just Cosmetic
Losing muscle mass isn’t just about not looking the same way you once did in a certain T-shirt, or a specific pair of jeans. Low muscle mass is linked to a host of health factors such as:
Higher risk of falls
Slower recovery from injury or surgery
Loss of independence
Higher hospitalisation rates
Higher overall mortality
Muscle is not just for athletes, or bodybuilders. Muscle is a form of life insurance. It’s savings in the bank for a future version of you who slips on the stairs at age 68. It’s likely the difference between a “bruise and a story” instead of “a potential hip fracture and six long months of rehab.”
“But I’m Active. I Walk…”
Any form of movement is better than no movement at all. Walking is excellent for your cardiovascular health, mood, blood glucose control, and general day-to-day energy. So by all means, keep walking!
But walking in isolation won’t protect you fully against anabolic resistance.
Why? Because anabolic resistance responds to mechanical tension — stimulus on the muscle. In the vast majority of circumstances, that means resistance training.
To be completely clear, we’re not talking about entering bodybuilding competitions, daily gym selfies, or attempting to deadlift your car.
We’re talking about 2-3 short resistance-focused sessions per week. Lifting with control, through safe ranges, at an effort level that feels like we’re generating stimulus on the muscle tissue itself.
Even small amounts of resistance training — literally a few sets of pushes, pulls, squats, hinges, carries etc., twice per week — can help older adults maintain or even build lean mass. That’s huge.
Because remember back to the cast experiment we mentioned above: activity protects the machinery.
Older adults who perform regular strength training can show similar anabolic responses to protein as younger adults. Take a moment to read that line again.
The implication isn’t “a bit better than average for their age". Comparable to younger adults.
The Silent Problem: Most Individuals Aren’t Resistance Training
Here’s the uncomfortable gap between what we know both scientifically and anecdotally to be true, and what we’re actually doing.
As of the 2023 NHS Health Survey for Adult Physical Activity, only 32% of adults over the age of 16 met the muscle-strengthening guidelines. With these percentage values dropping across both genders for each decade of life, with 23% (55-64yrs), 19% (65-74yrs), and 10% (75yrs+) of adults meeting these guidelines.
The majority of individuals heading into their 60’s, 70’s, and beyond, are doing so with:
Low muscle mass
Low strength values
Low protein intake
High levels of inactivity
Worsening insulin resistance
And then we act surprised when frailty seems to arrive in our aging population “all of a sudden.”
It wasn’t sudden, it’s compound interest in reverse.
Why Supplements Sell and Dumbbells Don’t
It’s increasingly easy to see why supplements, shakes, injections, peptides, and “miracle diets” all seem to get so much traction. They offer a fantasy. Do nothing differently than your current existence, take this shiny new thing, and watch your health and fitness problems dissolve.
Taking something is cognitively easier than changing how you fundamentally live your life.
Anyone who has been in a gym session will attest to the fact that resistance training by contrast, is inconvenient. You have to schedule it. You have to learn. You have to tolerate mild discomfort during, and possible soreness afterwards. You have to show up again next week. For weeks, months, and years on end.
But that inconvenience is the point. Muscle tissue matters, you need create a signal to keep hold of it.
The RDA Trap and “Good Enough”
One final detail that matters inside this equation.
The protein RDA (the number you’ve likely seen quoted as “enough protein per day” by the NHS) is set at a level that aims to prevents clinical deficiency — not at a level that optimises ageing, function, or long-term independence.
So the real world picture when you’re consuming just the RDA (0.75g/kg of bodyweight) starts to look like this:
You eat “enough” by official guidance, but it’s not actually enough to meaningfully stimulate muscle.
You don’t resistance train.
You become less sensitive to the protein that you do eat.
The slow creep of sarcopenia (age-related decline is muscle mass) begins.
The Takeaways
Let’s make this as practical as possible.
Eat Like Muscle Matters to You. Aim for 1.2-1.6g/kg of bodyweight per day. With meaningful protein source at each meal. Especially as you get older. Think lean meats, eggs, Greek yoghurt, fish, beans, lentils. Don’t guess, if there’s going to be one thing nutritionally that you do track, make it protein. Treat it as a target, not an afterthought.
Resistance Train Twice (or Thrice?…) a Week. 2-3 short resistance training sessions per week can preserve or even build muscle mass. Machines, Dumbbells Barbells, Kettlebells, resistance bands, bodyweight. It doesn’t need to be perfect form on highly technical movements. You just need to ask your muscles to work. Reach out to a Coach or Personal Trainer, even if it’s just for a few sessions, to get you started.
Treat Muscle as Health, Not Vanity. Holding onto strength isn’t about chasing after the last residuals of some younger version of yourself. It’s about securing future autonomy. A stronger you at 70 is harder to knock over, harder to hospitalise, and harder to keep down in general.
Stop Blaming Age For What Inactivity is Likely Causing. This isn’t denial of biology, we all age, hormone levels do shift, recovery does slow, appetite of course changes. But inactivity accelerates decline like lighter fuel on a fire.
Start Now, Not “When Things Calm Down”. It’s always tempting to say, “I’ll focus on this properly when work has settled down”, or “…once the kids are older”, or “…once I retire”. Remember, you won’t notice the cost until it’s too late.
The Slightly Uncomfortable Truth
If you’re 65, lifting twice per week, eating a meaningful amount of protein, and staying physically engaged, you may not be “experiencing aging” in the same way most people mean it conventionally.
If you’re 40, mostly sedentary, under-eating protein (and possible over eating everything else…), and assuming you’ll “sort out” your health and fitness later, you may already be banking the physical reality most people would blame on their 70s.
That’s not your body giving up on you. It’s doing exactly as the inputs would suggest it does. It’s responding, very logically, to the past 5, 10, or even 20 years of instructions it’s been given.
The hopeful part is that, of course, you’re in control of the instructions.
AK.