"Eat 1 gram of protein per pound of bodyweight" is the most repeated advice in fitness. But where does that number come from? Is it too low? Too high? And does it actually matter?
Let's look at what the research says. Not one study. Dozens.
The definitive meta-analysis
In 2018, Morton et al. published the largest meta-analysis on protein intake and muscle growth to date in the British Journal of Sports Medicine (source). They analyzed 49 studies with 1,863 participants.
Their conclusion: protein intakes of 1.6g/kg/day (0.73g/lb) maximized gains in muscle mass. Anything above 2.2g/kg (1g/lb) showed no additional benefit.
The "1g per pound" rule isn't wrong. It's just the ceiling, not the minimum. You're leaving nothing on the table at 0.73g/lb, and anything beyond 1g/lb is expensive urine.
The per-meal dose
Total daily protein matters most, but distribution matters too.
Schoenfeld and Aragon (2018) reviewed the evidence on protein timing and concluded that spreading intake across 4-5 meals of 0.4-0.55g/kg each optimizes muscle protein synthesis (source).
For a 180-pound lifter (82kg):
- Per meal: 33-45g protein
- Meals per day: 4-5
- Daily total: 131-180g
This is where meal frequency matters. Two 80g protein meals don't stimulate MPS as effectively as four 40g meals.
Does it change when cutting?
Yes. When you're in a caloric deficit, protein needs increase. Your body is more likely to break down muscle for energy when calories are restricted.
Helms et al. (2014) in the Journal of the International Society of Sports Nutrition recommended 2.3-3.1g/kg of lean body mass during caloric restriction for lean, resistance-trained individuals (source).
That's significantly higher than the 1.6g/kg baseline. If you're cutting, eat more protein, not less.
The practical numbers
Here's a quick reference table based on bodyweight and goal:
| Bodyweight | Maintenance/Bulking | Cutting |
|---|---|---|
| 140 lbs (64kg) | 102-140g/day | 120-160g/day |
| 160 lbs (73kg) | 117-160g/day | 135-180g/day |
| 180 lbs (82kg) | 131-180g/day | 155-205g/day |
| 200 lbs (91kg) | 146-200g/day | 170-225g/day |
| 220 lbs (100kg) | 160-220g/day | 190-250g/day |
Quality matters
Not all protein is created equal. Leucine content drives MPS, and animal proteins contain more leucine per gram than most plant proteins.
Highest leucine sources:
- Whey protein: ~12% leucine
- Eggs: ~8.5% leucine
- Chicken breast: ~7.5% leucine
- Beef: ~8% leucine
- Soy protein: ~7.5% leucine
The leucine threshold for maximal MPS stimulation is about 2.5-3g per meal. A 30g serving of whey hits 3.6g leucine. You'd need about 40g of most whole food proteins to hit the same threshold.
This doesn't mean plant protein can't build muscle. It can. You just need more of it per meal, or you need to combine sources.
Timing: does it matter?
Less than you think.
The "anabolic window" (eat protein within 30 minutes post-workout or lose your gains) has been largely debunked. A 2013 meta-analysis by Schoenfeld et al. found no significant benefit to immediate post-workout protein consumption when total daily intake was controlled (source).
That said, it's not a bad idea to eat within 2 hours of training. Not because of a magical window, but because your post-workout meal is one of your 4-5 daily protein doses, and skipping it means you're missing a dose.
Stop overcomplicating this
Here's what actually matters, in priority order:
- Hit your daily total (1.6-2.2g/kg)
- Spread it across 4+ meals (~0.4-0.55g/kg each)
- Increase protein when cutting (2.3-3.1g/kg of lean mass)
- Prioritize leucine-rich sources (whey, eggs, meat, fish)
- Don't stress the timing beyond eating regularly
The bottom line
You probably need less protein than the supplement industry tells you, but more than you're currently eating. Hit 1.6-2.2g per kg of bodyweight, spread across 4+ meals, and you're covering 95% of the protein puzzle. Everything else is optimization at the margins.
Track your protein like you track your lifts. It's the one nutritional variable that has the most direct, proven impact on muscle growth.