When I turned 40, my nutrition approach stayed the same as it had been in my thirties. Same protein intake, same meal timing, same general structure. My training was consistent. Recovery started feeling a bit slower, but I put it down to ageing.
Then I looked at the research on protein requirements after 40, and it changed how I eat.
The 0.8g/kg Myth
The RDA for protein is 0.8 grams per kilogram of bodyweight per day. You'll see this cited everywhere as the "recommended" protein intake. It is the minimum required to prevent deficiency-related nitrogen loss in a sedentary adult. It is not optimised for muscle retention, recovery, body composition, or healthy ageing.
For a 90kg man, 0.8g/kg means 72 grams of protein per day. If you're training, over 40, and trying to maintain or build muscle — 72 grams is not going to cut it.
The research on active men over 40 consistently points to requirements in the range of 1.6–2.2g per kg of bodyweight for muscle mass maintenance and growth. For a 90kg man, that's 144–198 grams per day. Roughly double the RDA.
[Source: Morton RW et al., 2018 — A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength — British Journal of Sports Medicine, 52(6):376–384]
Why the Requirement Goes Up After 40
This is the part most people don't know, and it's the reason the research on protein after 40 is different to the research on younger adults.
Anabolic Resistance
After around 35–40, muscle protein synthesis (MPS) — the process that builds and repairs muscle — becomes less sensitive to the anabolic stimulus of protein intake. Younger men can trigger a robust MPS response with a moderate dose of high-quality protein. Older men need a higher dose to achieve the same response.
This is called anabolic resistance — the muscle's diminished sensitivity to both resistance exercise and dietary protein as a growth stimulus.
The practical implication: the per-meal protein dose that optimally stimulates MPS increases with age. A 20-year-old may maximise MPS with 20–25g of leucine-rich protein. A 45-year-old likely needs 35–40g per meal to achieve the same response.
[Source: Moore DR et al., 2015 — Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men — Journal of Gerontology Series A, 70(1):57–62]
Lower Testosterone Amplifies the Problem
Testosterone amplifies the MPS response to protein and exercise. As testosterone declines with age, the anabolic signal from both training and protein intake is partially blunted. Higher protein intake partially compensates for this — more substrate available means less dependence on a hormonal amplifier.
Men who are addressing testosterone optimisation (D3, magnesium, zinc, ashwagandha — or for those with clinical deficiency, TRT) get more out of their protein because the hormonal environment is working better. The two strategies are complementary.
Reduced Absorption Efficiency
Gastric acid production declines with age. This matters for protein because stomach acid is the first step in protein digestion — it denatures proteins and activates the pepsin enzymes that begin breaking peptide bonds. Lower acid means less efficient initial protein processing.
This is one reason why the protein quality and completeness matters more at 40+ than at 20 — incomplete digestion means less of what you eat actually reaches your muscle tissue as amino acids.
How Much Per Meal Matters
Total daily protein matters. Distribution per meal also matters, and this is more important over 40 than under 40.
The research on MPS per meal shows a ceiling effect — consuming more protein in a single meal than can be used for MPS results in the excess being oxidised for energy rather than used for muscle protein synthesis. That ceiling is higher in older men (because more is needed to hit the threshold), but it still exists.
Practical target: Aim for 35–50g of high-quality protein per main meal, spread across 3–4 meals per day. Breakfast protein is particularly important — many men under-eat protein at breakfast, starting the day with MPS suppressed.
A strong protein breakfast example: 4 eggs + 150g Greek yoghurt + 30g whey in a shake = approximately 55–60g protein. Total daily MPS stimulus looks very different with that breakfast than with cereal and milk.
Protein Quality: Not All Sources Are Equal
Protein quality is determined primarily by its amino acid profile — specifically its leucine content and overall essential amino acid (EAA) profile. Leucine is the key trigger for MPS; the other EAAs provide the building blocks.
High-quality sources (most relevant for this site's audience)
Whey protein: The gold standard for leucine content and MPS stimulation. Approximately 10–11g leucine per 100g protein, complete EAA profile, rapid absorption. The best protein supplement for around-training consumption. No other supplement has a better evidence base for muscle protein synthesis.
Eggs: Complete protein, high leucine (8–9g per 100g protein), high bioavailability. The comparison of whole eggs vs. egg whites shows whole eggs produce greater MPS response — the yolk lipids appear to enhance amino acid utilisation. [Source: Churchward-Venne TA et al., 2012]
Lean meat (beef, chicken, turkey): Complete profile, good leucine content. Red meat provides additional creatine (approximately 2–5g per 500g of raw beef), haem iron, and zinc — all relevant for testosterone and performance.
Oily fish (salmon, mackerel, sardines): Complete protein plus omega-3 fatty acids. EPA and DHA from oily fish have a direct anabolic role — they reduce muscle protein breakdown and improve the MPS response to protein feeding. Men eating oily fish 3× per week are getting a protein and anabolic benefit that goes beyond the amino acid content. [Source: Smith GI et al., 2011 — Dietary omega-3 fatty acid supplementation increases the rate of muscle protein synthesis in older adults — American Journal of Clinical Nutrition]
Greek yoghurt and cottage cheese: Casein-based (slow-release). Good for pre-bed consumption — casein's slower digestion rate provides a more sustained amino acid release overnight, supporting overnight MPS.
The Plant Protein Question
Plant proteins are lower in leucine and missing or low in one or more essential amino acids (usually lysine, methionine, or leucine). For men over 40 with already-elevated protein requirements and anabolic resistance, plant proteins require higher quantities to achieve the same MPS stimulation as animal proteins.
This doesn't mean plant protein is useless — it means if you're primarily plant-based, your protein target should be at the higher end (2.0–2.5g/kg) and you should focus on combining sources to ensure complete EAA profiles.
Practical Targets for Men Over 40
Sedentary or lightly active: 1.4–1.6g/kg bodyweight
Regularly training (3–5× per week): 1.8–2.2g/kg
Actively training and body composition focused: 2.0–2.4g/kg
In a caloric deficit (cutting): 2.2–2.5g/kg (higher protein helps preserve muscle during deficit)
For a 90kg man training 4× per week: 162–198g protein per day is the evidence-based target.
The Practical Challenge
The biggest barrier most men over 40 have with protein isn't the knowledge — it's actually hitting the numbers consistently.
162–198g protein per day from whole food sources is a lot of eating. Solutions:
Whey protein is your friend. One scoop of good-quality whey post-training (25–30g protein) plus another in a shake elsewhere in the day gets you 50–60g without adding significant meal volume.
High-protein breakfast is non-negotiable. Starting the day with 40–50g protein means you're already well ahead by the time you get to lunch. It also reduces hunger later in the day.
Track for two weeks. Most men who say they eat "plenty of protein" are surprised when they track it. Actual numbers are usually 40–60% of where they should be. Track with an app (MyFitnessPal, Cronometer) for two weeks to get an accurate picture, then adjust. You don't need to track forever — once you know what the numbers look like, you can hit them by eye.
The Short Version
The RDA for protein was designed to prevent deficiency in sedentary people. If you're over 40, training, and interested in your body composition and metabolic health, your protein requirement is roughly double that — in the range of 1.8–2.4g per kilogram of bodyweight per day, with 35–50g per main meal to maximise muscle protein synthesis. The mechanism is anabolic resistance: your muscles need a higher protein dose to trigger the same synthesis response that a younger man gets from less. Fix breakfast first, add a quality whey shake, focus on leucine-rich sources (whey, eggs, lean meat, oily fish), and track for two weeks to get honest with your actual intake.
Related Guides
- Protein Intake Over 40 Guide
- Best Protein Sources Uk
- Post Workout Nutrition Guide
- Meal Prep Guide Men Over 40
Seb covers nutrition and supplementation for active men over 35. He writes from evidence, not orthodoxy.