You've probably been eating roughly the same way for twenty years. Same breakfast, same rough sense of what a decent meal looks like.
Your muscles have changed how they respond to it.
What actually changed
There's a phenomenon called anabolic resistance, and it's one of the better-documented changes that comes with age.
In a younger adult, a moderate serving of protein — call it 20 grams — triggers a solid muscle-building response. Muscle protein synthesis kicks up, the body uses the material, and you get on with your day.
In an older adult, that same 20 grams produces a blunted version of the same response. The muscle is less sensitive to the amino acid signal. Same food, less effect.
Nothing you did wrong. It's a metabolic shift that happens whether you're a lifelong lifter or someone who's never touched a barbell.
The number
The most-cited guidance comes from the PROT-AGE Study Group, a panel convened by the European Union Geriatric Medicine Society, published in the Journal of the American Medical Directors Association.
Their finding on per-meal intake: the anabolic threshold is higher in older adults — roughly 25 to 30 grams of protein per meal, containing about 2.5 to 2.8 grams of leucine. Younger adults reach the same response on less.
On daily intake, they recommend:
- 1.0-1.2 g per kg of bodyweight for healthy adults over 65
- 1.2 g/kg or more for those who are exercising and otherwise active
- 1.2-1.5 g/kg for most older adults dealing with acute or chronic illness
For comparison, the standard adult RDA is 0.8 g/kg.
If you're 85 kg and training, that middle line puts you at 102 grams a day as a floor — not a target, a floor.
Three things that follow
Spread it out.
This is the practical consequence people miss. If each meal has to clear the threshold on its own, then three meals at 30 grams does more for you than one meal at 90 grams — even though the daily total is identical.
Most people's protein is heavily back-loaded. Toast for breakfast, a light lunch, then a big dinner that covers the day's total in one sitting. That pattern leaves two of three meals below threshold.
Breakfast is usually the easiest fix and the one with the most room in it.
Leucine is the trigger.
Leucine is the specific amino acid that signals muscle protein synthesis to start, which is why the PROT-AGE guidance names a leucine target and not just a protein target.
Animal sources clear it comfortably — whey, dairy, eggs, meat, fish. Most plant sources are lower in leucine per gram of protein, so hitting the same threshold takes a larger serving or a deliberate combination. That's a portion-size problem, not a reason to change how you eat.
Training and protein are one system.
Protein without loading doesn't build much. Loading without protein doesn't have the material to work with. The research on older adults consistently finds the combination outperforms either alone.
If you're already training, this is the half you might be under-doing.
The exception that matters
One group needs to run the opposite direction, and it's important enough to state plainly.
The PROT-AGE paper flags severe kidney disease — an estimated GFR below 30 mL/min/1.73m², in people not on dialysis — as a clear exception. Those individuals may need to limit protein intake, not increase it.
More generally: if you have any kidney condition, if you're on medication that affects kidney function, or if you simply don't know where your kidney numbers sit, that's a conversation with your doctor before you change anything. It's a routine blood test and worth having the number.
This isn't a disclaimer bolted on the end. It's a real fork in the guidance.
What to actually do this week
Don't overhaul anything. Just count for two days.
Write down what you actually eat and roughly how much protein is in it. Most people are surprised by two things: the daily total is lower than they assumed, and it's concentrated in one meal.
Then fix the weakest meal. That's usually breakfast, and usually it's a 30-second decision rather than a lifestyle change.
That's the whole intervention. The research is more interesting than the action it recommends, which is normally a good sign.
Everything above summarizes published guidance and research. It isn't personalized nutrition advice. Protein needs change with kidney function, medication and medical history — if any of those apply to you, talk to your doctor or a registered dietitian before making changes.
Sources
- Bauer J et al. Evidence-Based Recommendations for Optimal Dietary Protein Intake in Older People: A Position Paper From the PROT-AGE Study Group. Journal of the American Medical Directors Association, 2013.
- Protein intake and exercise for optimal muscle function with aging: Recommendations from the ESPEN Expert Group. Clinical Nutrition, 2014.
- Protein Requirements for Master Athletes: Just Older Versions of Their Younger Selves.
- The impact of nutritional intervention and resistance training on muscle strength and mass in healthy older adults — a comparative analysis.
About this article
Written by the IRONBACKPACK editorial team. We make training gear — we're not clinicians, and we don't pretend to be. Everything here is sourced to published research, linked so you can read it yourself, and nothing here is medical advice. Where the evidence is uncertain, we say so.
Last updated: August 2026
