Protein Sweet Spot for Lifters: 1.6 g/kg/day
More protein isn't always better - here's the intake that maximizes muscle gains.
The Myth: You Need Sky-High Protein to Build Muscle
Protein is vital for muscle growth, but where's the point of diminishing returns? A 2017 meta-analysis of 49 randomized controlled trials (including over 1,800 participants) explored how protein intake influences gains in fat-free mass and strength (PubMed28698222).
Findings
Strength and Fat-Free Mass
Protein supplementation led to significant increases in one-repetition max strength and lean body mass compared with control groups (PubMed28698222). This effect was observed across various populations and training protocols.
Dose-Response Relationship
Gains plateaued at about 1.6 g/kg/day. Intakes beyond 1.62 g/kg/day did not produce further improvements (PubMed28698222). This represents a clear inflection point - the sweet spot where benefits max out.
The Numbers: For a 75 kg (165 lb) lifter, the optimal intake is approximately 120 grams of protein per day. Consuming 150-180+ grams provides no additional muscle-building benefit and may displace other important nutrients. This isn't to say higher intakes are harmful - just that they don't enhance muscle growth beyond the 1.6 g/kg threshold.
Training Status
Benefits were more pronounced in individuals with resistance training experience; novices saw less effect from extra protein, likely because training itself drove most gains (PubMed28698222). This makes sense - beginners respond so robustly to training that protein intake above basic needs doesn't provide much extra advantage.
Age Effects
Younger participants responded better than older ones, but sample sizes were small. Older adults may have slightly higher protein needs due to anabolic resistance, though the meta-analysis couldn't definitively establish separate recommendations.
| Protein Intake (g/kg/day) | Muscle Growth | Strength Gains | Recommendation |
|---|---|---|---|
| <0.8 (RDA) | Suboptimal | Limited | Insufficient for lifters |
| 1.0-1.4 | Good response | Good gains | Decent but not optimal |
| 1.6-1.8 | Maximal response | Maximal gains | Optimal range (SWEET SPOT) |
| 2.0-2.2 | No additional benefit | No additional benefit | Safe but unnecessary |
| >2.2 | No additional benefit | No additional benefit | Potential downsides, no upside |
Practical Recommendations
Aim for 1.6 g/kg/day
Spread across three to four meals to optimize synthesis. For a 75 kg lifter, that's 120 g of protein. Here's how this might look:
- Breakfast: 30 g (3 eggs + Greek yogurt)
- Lunch: 35 g (150 g chicken breast + quinoa)
- Dinner: 35 g (180 g salmon + lentils)
- Snack: 20 g (protein shake or cottage cheese)
Quality Counts
Prioritize complete proteins - dairy, meat, fish, eggs, soy - plus varied plant proteins for vegetarians:
High-Quality Protein Sources (per 100g)
- Chicken breast: 31 g protein
- Salmon: 25 g protein
- Greek yogurt (non-fat): 10 g protein
- Eggs: 13 g protein
- Lean beef: 26 g protein
- Tofu (firm): 17 g protein
- Lentils (cooked): 9 g protein
- Cottage cheese: 11 g protein
Distribution Matters
While total daily intake is most important, distributing protein across meals optimizes muscle protein synthesis:
- Target 0.4 g/kg per meal: For a 75 kg person, that's 30 g per meal
- 3-4 meals per day: Allows adequate spacing (3-5 hours) between protein doses
- Include protein before bed: Casein or slow-digesting protein supports overnight synthesis
- Post-workout matters but isn't magical: Get protein within a few hours; the "anabolic window" is wider than once thought
Above 2.2 g/kg/day Offers Little Extra
Exceeding this may strain kidneys in susceptible individuals. While healthy kidneys can handle high protein, very high intakes provide no muscle-building advantage and come with potential downsides:
Potential Issues with Very High Protein Intake
- Nutrient displacement: Excessive protein crowds out carbohydrates and fats needed for energy and hormonal health
- Kidney stress: While not harmful to healthy kidneys, those with pre-existing issues should be cautious
- Digestive discomfort: Many people experience GI issues with very high protein
- Cost: Protein is expensive; spending more for no gain isn't efficient
- Reduced performance: Inadequate carbohydrates can impair training intensity
Combine with Training
Resistance exercise is the key driver of muscle growth; protein supports, but doesn't replace, hard work.
Training is Non-Negotiable: No amount of protein will build muscle without the training stimulus. The meta-analysis clearly showed that protein supplementation benefits those engaged in regular resistance training - it amplifies the adaptation to training stress. Think of protein as the raw material and training as the blueprint that tells your body what to build.
Optimal Protein + Training Combination
- Progressive overload: Consistently increasing training demands
- 1.6 g/kg/day protein: Provides sufficient amino acids for adaptation
- Adequate calories: Slight surplus for muscle building, maintenance for recomposition
- Quality sleep: 7-9 hours for optimal recovery and protein synthesis
- Consistency: Both training and nutrition must be sustained over months
Special Populations
Vegetarians and Vegans
Plant proteins are slightly less bioavailable, so aim for the higher end (1.8-2.0 g/kg/day). Combine complementary proteins:
- Rice + beans
- Hummus + whole wheat pita
- Peanut butter + whole grain bread
- Consider leucine supplementation if plant protein dominates
Older Adults (>50 years)
Anabolic resistance may benefit from slightly higher protein (1.8-2.0 g/kg/day) and per-meal doses (0.4-0.5 g/kg). Resistance training becomes even more critical to preserve muscle mass.
During Fat Loss
Higher protein (2.0-2.4 g/kg/day) can help preserve lean mass in a caloric deficit. Protein's high thermic effect and satiety also support adherence to calorie restrictions.
Elite Athletes
Endurance athletes have lower protein needs (~1.2-1.4 g/kg/day) than strength athletes. Mixed training modalities benefit from intakes around 1.6-1.8 g/kg/day.
Common Protein Myths
Myth: The body can only absorb 30 g per meal
Reality: Your body absorbs virtually all dietary protein. What's limited is how much maximally stimulates muscle protein synthesis per feeding (~0.4 g/kg). Extra protein is used for other physiological processes or energy.
Myth: You must eat protein immediately post-workout
Reality: The "anabolic window" is several hours wide. As long as you eat protein within 3-5 hours post-training, you'll optimize synthesis. Total daily intake matters more than precise timing.
Myth: More protein = more muscle
Reality: Beyond 1.6-1.8 g/kg/day, extra protein doesn't enhance muscle growth. Training stimulus, total calories, sleep, and consistency matter more.
Myth: Plant protein can't build muscle
Reality: Plant proteins absolutely support muscle growth when consumed in adequate amounts and combined properly. The key is variety and slightly higher total intake to account for lower bioavailability.
The Final Word: For individuals engaged in regular resistance training, 1.6 g/kg/day represents the sweet spot - the inflection point where muscle and strength gains plateau. Going below this leaves gains on the table; going significantly above provides no additional benefit for hypertrophy or strength. Focus on hitting this target consistently, distributing protein across meals, prioritizing high-quality sources, and training hard. Let the 1.6 g/kg/day guideline simplify your nutrition, freeing mental energy for what really drives results: progressive, consistent training.