The official dietary reference for protein — 0.8g per kilogram of body weight — was designed to prevent deficiency in sedentary adults. It was never intended as an optimal target for people who exercise, try to build muscle, or want to preserve lean mass while losing fat.
If you're relying on that number, you're almost certainly under-eating protein.
The Official Numbers vs What Research Shows
RDA: 0.8g/kg — this is the minimum to avoid muscle wasting in sedentary adults. Not the optimal amount. Not the sports nutrition recommendation.
Research consensus for active adults: 1.6–2.2g/kg of body weight per day.
A 75 kg person:
- RDA target: 60g/day
- Research-supported target: 120–165g/day
The gap is enormous, and it has real consequences for body composition, recovery, and satiety.
Why Active People Need More
Muscle protein turnover. Resistance training breaks down muscle protein. For muscle to be built back larger and stronger, net protein synthesis must exceed protein breakdown. This requires a continuous supply of amino acids — specifically leucine, which triggers the mTOR pathway for muscle synthesis.
Thermic effect. Protein has a thermic effect of 25–30% — meaning you burn roughly a quarter of protein calories just digesting it. This compares to 6–8% for carbohydrates and 2–3% for fat. Higher protein intake directly increases metabolic rate.
Satiety. Protein is the most satiating macronutrient per calorie. Higher protein diets reduce hunger hormone ghrelin and increase satiety hormones PYY and GLP-1. For fat loss, this is the most underrated benefit.
Muscle preservation during cuts. During a calorie deficit, inadequate protein accelerates muscle loss. Studies consistently show that higher protein intake (2g+/kg) during cuts dramatically reduces lean mass loss compared to standard recommendations.
Protein Requirements by Goal
Building muscle (lean bulk)
1.6–2.2g/kg/day
The 2017 Morton et al. meta-analysis of 49 studies found protein intakes above 1.62g/kg produced diminishing returns for muscle gain in most populations. Going higher (2.2g+) doesn't hurt and provides a margin — useful given that protein tracking isn't perfectly accurate.
Cutting (fat loss while preserving muscle)
2.0–2.4g/kg/day
Requirements go up during a deficit. The body has a greater tendency to use protein for fuel when carbohydrate and fat intake are reduced. Increasing protein intake during cuts compensates. Some studies support 2.4g/kg during aggressive deficits for trained individuals.
Maintenance
1.6g/kg/day
If not in a deficit or surplus and training regularly, 1.6g/kg maintains muscle mass and supports recovery.
Older adults (45+)
1.6–2.0g/kg/day minimum
Muscle protein synthesis efficiency declines with age — a phenomenon called anabolic resistance. Older adults require higher protein doses per meal to trigger the same anabolic signal as younger adults. 40g per meal (vs the commonly recommended 25–30g) is often more effective for those over 60.
Sedentary adults
1.0–1.2g/kg/day
Even without exercise, more protein than the RDA helps with satiety, metabolic health, and lean mass maintenance. The RDA is not an optimal target for anyone.
Distribution Matters as Much as Total
Recent research suggests muscle protein synthesis is limited by the leucine threshold per meal: you need approximately 2–3g of leucine per meal to maximally stimulate synthesis, which corresponds to roughly 25–40g of protein per meal depending on the source.
Beyond ~40g in a single dose, muscle protein synthesis doesn't increase further (though the excess protein is still useful calorically and metabolically).
This means:
- Spreading 160g of protein across 4 meals (40g each) is superior to eating 160g across 2 meals (80g each) for muscle building
- Getting all your protein in one massive meal (OMAD approach) blunts the anabolic signal compared to distributed intake
For fat loss alone, distribution matters less. For muscle building or preservation, aim for 4 protein-rich meals across the day.
Best Protein Sources by Leucine Content
Leucine is the amino acid that most directly triggers muscle protein synthesis. Animal proteins are generally higher in leucine per gram:
| Source | Protein per 100g | Leucine per 100g |
|---|---|---|
| Whey protein | 80g | ~10g |
| Chicken breast | 31g | ~2.4g |
| Tuna | 30g | ~2.5g |
| Eggs | 13g | ~1.1g |
| Greek yoghurt | 10g | ~1.0g |
| Lentils | 9g | ~0.7g |
| Tofu | 8g | ~0.6g |
Plant proteins are lower in leucine and sometimes incomplete (missing essential amino acids). Those following plant-based diets should consume 20–30% more total protein to compensate, and combine complementary sources (e.g., rice + legumes).
Common Mistakes
Counting protein from all food sources. Protein supplements are often credited accurately, but people miss the significant protein content in rice, oats, vegetables, and bread. Track everything.
Underestimating serving sizes. A "chicken breast" varies from 100g to 300g. Weigh your food. The difference between estimated and actual protein intake is often 30–50g/day.
Relying on protein bars. Most contain 15–20g of protein — useful as a supplement, not a meal. Check the actual leucine content if muscle building is your goal; many bars use collagen protein, which is low in leucine and a poor trigger for muscle synthesis.
Ignoring protein quality. 50g of plant protein from a single source is not equivalent to 50g of whey. If you're primarily plant-based, track your leucine as well as total protein, or increase total intake.
Practical Targets
Quick reference by body weight, at 2g/kg:
| Body weight | Daily protein target |
|---|---|
| 60 kg | 120g |
| 70 kg | 140g |
| 80 kg | 160g |
| 90 kg | 180g |
| 100 kg | 200g |
If you're significantly overweight, use your target body weight rather than current weight for calculations — otherwise you'll be calculating a protein target inflated by fat mass.
The Bottom Line
For active adults, 1.6–2.2g of protein per kilogram of body weight per day is the evidence-based target. During a calorie deficit, push towards the upper end. Distribute intake across 3–4 meals.
The RDA of 0.8g/kg keeps you alive. The research-supported range keeps you lean, strong, and recovering.
Hit protein first in every meal. Build the rest of your diet around it.