Why the same protein shake may do less for you than it used to, and how to adjust if you’re over 40 and want to keep your muscle.
Eating “enough” protein may not be enough as you get older. Your muscles can get pickier about how much they need at once.
Why the same shake does less
Researchers call it anabolic resistance: older muscle responds less to the same dose of amino acids, the building blocks of protein. In a study of 44 young and old men, resting muscle building was the same in both groups, but the older men responded less to amino acids. Those men were well past 40, so treat it as the direction of travel, not a cliff at your birthday.
Key things to know
- Dose per meal matters — in older men, muscle building maxed out at about 0.40 g of protein per kg of body weight per meal, versus 0.24 g/kg in young men.
- Daily totals go up — an expert panel recommends at least 1.0–1.2 g/kg a day for people over 65, and more if you exercise.
- Lifting is half the deal — in a review of 78 trials, protein plus resistance training improved muscle mass and strength in older adults, though the certainty was low to moderate.
How much per meal
For an 80 kg (176 lb) person, 0.40 g/kg works out to about 32 g of protein in a meal. The same expert panel puts the per-meal target at 25–30 g, with roughly 2.5–2.8 g of leucine, an amino acid that helps switch muscle building on. Eggs, dairy, fish, and poultry are easy ways to get there.
Key takeaway: Aim for a solid serving of protein at each meal, not one huge dinner.
How much per day
The panel’s numbers are for people over 65, so in your 40s and 50s they’re a sensible upper range, not a rule. If you train, starting near 1.2 g/kg (about 96 g at 80 kg) is reasonable. Check with a clinician first if you have kidney disease, since the same paper flags severe kidney disease as an exception.
Putting it into practice
- Split protein across three or four meals instead of backloading dinner.
- Lift two or three times a week. Our muscle maintenance after 40 guide covers how.
- Make it automatic. Hitting a per-meal target is a habit problem, and that’s where Proteinly helps: it’s protein-first with no calorie counting, and its automatic eating timer reminds you to eat every 2 hours so protein shows up through the day. It’s a consistency tool, not a muscle trick.
Frequently asked questions
Is it true that protein doesn’t build muscle after 60?
Not really. Protein still matters; the research above shows it works alongside resistance training, so you need both.
Do I need whey?
Whey came out on top in the network meta-analysis, but food that hits your per-meal target works too.
Should I eat as much protein as possible?
No. Aim for the ranges above, and talk to a clinician first if you have kidney disease.
Next steps
Pick one meal this week that’s short on protein and fix it, then build from there. Find more at Proteinly, TikTok, and Instagram. Build the Habit. Build the Body.
Idea from Smart Mindset’s video “Protein Isn’t What Builds Muscle After 60”; facts checked against the sources above.