In This Article
Key Takeaways
- The RDA of 0.36g/lb (0.8g/kg) prevents deficiency — it's not optimal for active people or body composition
- Active adults benefit from 0.7–1.0g/lb (1.6–2.2g/kg) body weight per day
- Protein in a calorie deficit should be at the higher end to preserve muscle (0.8–1.2g/lb)
- Older adults (50+) need more protein per kg than younger adults to stimulate the same muscle protein synthesis
- Spreading intake across 3–4 meals of 25–40g protein each maximizes muscle protein synthesis
RDA vs. Optimal Intake
The Recommended Dietary Allowance (RDA) for protein is 0.8g per kg (0.36g per lb) of body weight per day. For a 150 lb (68 kg) person, that's about 55g of protein daily.
The RDA is set at 2 standard deviations above the average requirement to cover 97.5% of the population — meaning it's designed to prevent deficiency, not to optimize muscle mass, satiety, metabolic rate, or body composition.
A 2017 meta-analysis in the British Journal of Sports Medicine (Morton et al.) pooled 49 studies and found muscle gain plateaued at ~1.62g/kg/day (0.73g/lb/day) with resistance training. Other researchers argue for up to 2.2g/kg in certain contexts. The practical consensus among sports dietitians:
| Population | Recommended Range |
|---|---|
| Sedentary adults (minimum) | 0.8g/kg (0.36g/lb) |
| Active adults, general fitness | 1.2–1.6g/kg (0.55–0.73g/lb) |
| Resistance training (muscle gain) | 1.6–2.2g/kg (0.73–1.0g/lb) |
| Weight loss with exercise | 1.6–2.4g/kg (0.73–1.1g/lb) |
| Older adults (65+) | 1.2–1.6g/kg (0.55–0.73g/lb) |
| Endurance athletes | 1.2–1.6g/kg (0.55–0.73g/lb) |
Protein Targets by Goal
For Muscle Building
Research supports 1.6–2.2g/kg (0.73–1.0g/lb) per day for maximizing hypertrophy (muscle growth) when combined with progressive resistance training. Beyond 2.2g/kg shows diminishing returns in most studies. The "1g per lb" rule is a slight overestimate but provides a useful round number and a safety buffer.
For a 180 lb (82 kg) person training for muscle gain: 130–180g protein/day.
For Fat Loss
Protein needs actually increase during a calorie deficit. When calories are restricted, the body is more likely to catabolize muscle for energy. High protein intake (1.6–2.4g/kg) combined with resistance training minimizes this. The thermic effect of protein (~25–30%) also means you burn more calories digesting it, giving a small but real metabolic advantage.
For General Health (Sedentary)
Meeting the RDA (0.8g/kg) prevents deficiency. Eating slightly above this (1.0–1.2g/kg) provides satiety benefits and a buffer against age-related muscle loss, without being onerous to achieve through food alone.
Calculate Your Daily Protein Target
Get your protein goal based on body weight, activity level, and fitness goal.
Timing and Distribution
Total daily protein intake is more important than timing, but distribution does matter for muscle protein synthesis (MPS):
Optimal Meal Distribution
Research by Stuart Phillips and others shows MPS is maximized by consuming 20–40g of leucine-rich protein per meal, distributed across 3–5 meals. Eating 150g protein in one meal is less effective than spreading it into 4 meals of ~37g each.
| Meals/Day | Protein Per Meal (for 150g/day target) | MPS Optimization |
|---|---|---|
| 2 meals | 75g per meal | Suboptimal — excess not fully utilized |
| 3 meals | 50g per meal | Good |
| 4 meals | 37.5g per meal | Excellent |
| 5+ meals | 30g per meal | Good, but impractical for most |
Pre- and Post-Workout Protein
The "anabolic window" (eating protein immediately after training) is less important than previously thought. Research suggests that as long as you eat enough protein across the day, the specific timing around workouts matters little unless you train fasted. A protein-containing meal 1–2 hours before or after training covers any acute need.
Best Protein Sources
| Food | Serving | Protein | Leucine (key amino acid) |
|---|---|---|---|
| Chicken breast (cooked) | 100g | 31g | 2.4g |
| Lean beef (90/10) | 100g | 26g | 2.1g |
| Salmon (cooked) | 100g | 25g | 1.9g |
| Eggs (whole) | 2 large | 12g | 1.1g |
| Greek yogurt (plain, 0%) | 170g | 17g | 1.4g |
| Cottage cheese (1% MF) | ½ cup (113g) | 14g | 1.3g |
| Whey protein powder | 1 scoop (28g) | 22–25g | 2.5g |
| Tofu (firm) | 100g | 8g | 0.6g |
| Lentils (cooked) | 1 cup (200g) | 18g | 1.3g |
| Edamame (shelled) | 1 cup (155g) | 17g | 1.2g |
Complete vs. incomplete proteins: Animal proteins contain all essential amino acids in good proportions (complete). Most plant proteins are lower in one or more essential amino acids. Eating a variety of plant proteins across the day (rice + beans, for example) effectively provides all essential amino acids. Vegans may also benefit from slightly higher total protein intake to compensate for lower bioavailability of plant proteins.
Protein and Aging
After age 30, adults lose 3–5% of muscle mass per decade (sarcopenia). After 60, loss accelerates. Older adults have a blunted MPS response to protein — requiring more leucine per meal to stimulate the same MPS as a younger person. This is called "anabolic resistance."
Practical implications for adults over 50:
- Aim for 1.2–1.6g/kg/day minimum (higher than the RDA)
- Prioritize leucine-rich protein sources (dairy, meat, eggs, whey)
- Include protein at breakfast — older adults often eat protein-poor breakfasts
- Combine with resistance training — the single most effective intervention against sarcopenia
Frequently Asked Questions
The RDA of 0.36g/lb (0.8g/kg) is the minimum to prevent deficiency in sedentary adults — not an optimal target for active people. Research consistently shows higher intakes of 0.7–1.0g/lb (1.6–2.2g/kg) better support muscle protein synthesis, satiety, and body composition goals. Even for non-athletes, slightly above the RDA (0.5–0.6g/lb) improves satiety and provides a buffer against age-related muscle loss.
Protein is arguably the most important macronutrient during weight loss. It has the highest thermic effect (~25–30% of calories burned during digestion vs ~5–10% for carbs and ~0–3% for fat), significantly increases satiety hormones (GLP-1, PYY) and reduces hunger hormones (ghrelin), and preserves lean muscle mass during a calorie deficit — preventing the "skinny fat" outcome where weight drops but body composition worsens.
In healthy individuals without pre-existing kidney disease, high protein intake (up to 2.5–3.0g/kg/day) is not shown to harm kidney function. Multiple studies in healthy adults and athletes show no adverse effects. The concern applies specifically to people with existing kidney disease, for whom protein restriction may be clinically indicated. Healthy kidneys have robust filtration capacity that handles high protein diets effectively.
Yes — research shows consuming 25–40g of protein per meal (3–4 times per day) is more effective for stimulating muscle protein synthesis than eating the same total in 1–2 large meals. The muscle can effectively stimulate MPS with ~20–40g of protein per meal, with diminishing returns above that threshold. 3–4 protein-rich meals per day is the practical sweet spot for most people.