Protein recommendations have ranged from absurdly low (the RDA at 0.36 g/lb, which prevents deficiency but doesn’t support hypertrophy) to absurdly high (some bodybuilding lore at 2 g/lb of bodyweight or more, with no evidence to support it).
The actual answer, from the highest-quality meta-analysis on the question, sits in a much narrower band than either camp wants to admit.
The Morton Number
In 2018, Robert Morton and colleagues published a meta-analysis in the British Journal of Sports Medicine that pulled together every randomized trial on protein intake and resistance-training-induced hypertrophy. The pooled data identified a saturation point.
The number: ~1.6 grams of protein per kilogram of body weight per day. Roughly 0.7 g/lb.
Above 1.6 g/kg, the additional protein produced no further increase in lean mass gains in the trials reviewed. Below it, gains were measurably suppressed. The 95% confidence interval extended up to about 2.2 g/kg, suggesting some individuals may benefit from slightly more — but the bulk of the data converged at 1.6.
For a 175-pound lifter, that’s 127 grams per day. Not 250. Not 200. About 130.
This isn’t a license to undereat protein. It’s permission to stop force-feeding chicken breasts past the point of diminishing returns.
When You Might Want More
The 1.6 g/kg target is for healthy lifters in a maintenance or surplus, training for hypertrophy. Three populations may benefit from going higher (toward 2.0 to 2.4 g/kg):
- Lifters in a calorie deficit (cutting). Higher protein during weight loss preserves more lean mass. Helms et al. (2014) recommended 2.3 to 3.1 g/kg of fat-free mass during contest prep. For most cutters, that lands around 2.2 g/kg of total body weight.
- Older adults (50+). Anabolic resistance increases with age. Protein leucine thresholds rise. Targeting the upper end of the range is reasonable past 50.
- Highly trained advanced lifters in extreme volume blocks. Marginal returns — but real ones — have been observed in some long-running athletes.
For everyone else, 1.6 g/kg is the target. Above 2.2 g/kg, you’re displacing carbohydrate and fat that could be doing more for performance and body composition.
Distribution Matters
Total daily protein matters most. But within that total, distribution affects muscle protein synthesis (MPS).
The mechanism is the leucine threshold. Each meal needs roughly 2.5 to 3 grams of leucine to maximally stimulate MPS. That corresponds to about 0.4 g/kg of high-quality protein per meal — roughly 30 to 45 grams for most lifters.
Practical implication: spreading 130 grams across four to five meals (~30 g each) consistently outperforms eating 70 grams at dinner and skipping protein at breakfast. Research by Areta et al. (2013) and Mamerow et al. (2014) both supported even distribution over front-loaded or back-loaded patterns.
Bodyweight in lb × 0.7 = daily protein in grams. Divide by four meals. Hit each meal with a complete protein source — whey, chicken, beef, fish, eggs, dairy, or a soy/pea blend.
Quality vs Quantity
Not all protein hits the leucine threshold equally. Animal sources — whey, casein, eggs, beef, chicken, fish — are leucine-dense and complete (containing all nine essential amino acids in usable ratios).
Plant sources are more variable. Soy and pea isolates approach animal-source quality. Most other plant proteins (rice, hemp, beans alone) are lower in leucine and may need to be combined or eaten in larger quantities to hit the same threshold. Vegan lifters can absolutely build muscle — the protein math just has slightly different inputs. Studies on isocaloric, isonitrogenous diets have shown comparable hypertrophy outcomes when total protein and leucine are matched.
Common Mistakes
Chasing 200+ Grams at 165 Pounds
Common in bro-science circles. Below the saturation point, more protein helps. Above it, you’re just displacing other macros. The 165-lb lifter targeting 200 g/day is eating 75 g over the saturation point with no measurable benefit.
Eating One Massive Protein Meal
If your only protein source is a 60-gram dinner, you’re leaving MPS stimulation on the table. The body can use ~0.55 g/kg per meal effectively for MPS purposes (Schoenfeld & Aragon, 2018). The rest gets used for energy or oxidized.
Ignoring Protein at Breakfast
The longest gap in your eating window is overnight. Adding 25 to 40 grams of protein at breakfast is one of the simplest leverage points for lifters who’ve plateaued.
The Bottom Line
- 1.6 g/kg/day (~0.7 g/lb) is the research-backed saturation point for muscle growth.
- 2.2 g/kg may benefit cutters, older adults, and elite-volume lifters — not everyone.
- Spread protein across 4 to 5 meals at ~0.4 g/kg per meal to maximize muscle protein synthesis.
- Quality matters: prioritize complete protein sources with high leucine content.
- If you’re a 175-lb lifter targeting 250 g/day, you’re overshooting. 130 g, well-distributed, is the target.
REFERENCES
- Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384.
- Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018;15:10.
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20.
- Areta JL, Burke LM, Ross ML, et al. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol. 2013;591(9):2319-2331.
- Mamerow MM, Mettler JA, English KL, et al. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr. 2014;144(6):876-880.