Overview
This lecture explains protein quality, how much protein you need for muscle growth and health, and which protein sources optimize your results.
Protein Intake Recommendations
- Aim for about 1 gram of protein per pound of body weight per day for muscle growth.
- Lower intake (0.7–0.8 g/lb) is sufficient for maintenance and light training.
- Higher intake (1.25–1.3 g/lb) may benefit those training intensely or dieting for fat loss.
- Consuming too much protein is not harmful; too little can limit muscle growth or promote muscle loss.
Understanding Protein Quality
- Not all proteins are equal; “protein quality” refers to amino acid profile and digestibility.
- High-quality proteins match human amino acid needs and are well digested and absorbed.
- Low-quality proteins lack certain essential amino acids or are poorly digested.
Protein Digestibility Corrected Amino Acid Score (PDCAAS)
- PDCAAS scores range from 0 (lowest) to 1 (highest), indicating protein’s suitability for human needs.
- Typical cut-off: 0.9 (90%) or higher is “high-quality” protein.
- Examples:
- Animal proteins: eggs (1.0/100%), whey (1.04/104%), chicken/fish/beef (0.95–0.97/95–97%).
- Plant proteins: soy isolate (0.9/90%), quinoa (0.92/92%), tofu (0.93/93%). Most other plant sources score lower.
- Low scores: gelatin (0.08/8%), wheat (0.25/25%), rice (0.47/47%), lentils (0.58/58%), peanut butter (0.7/70%).
Practical Application: Building Meals
- At least 75% of your daily protein should come from high-quality sources (PDCAAS ≥ 0.9).
- The remaining 25% can be from lower-quality sources without major issues.
- Build every meal around a high-quality protein core (meat, eggs, dairy, soy, or high-quality vegan blends).
- Mixing certain plant proteins (e.g., beans and rice) can form a complete, higher-quality protein.
Key Terms & Definitions
- Amino Acids — Building blocks of proteins; essential ones must come from diet.
- PDCAAS — Protein Digestibility Corrected Amino Acid Score, measures protein quality based on human needs.
- High-Quality Protein — Protein source with PDCAAS ≥ 0.9, well-matched to human amino acid requirements and easily digested.
- Leucine — An amino acid important for triggering muscle growth.
- Protein Core — The main high-quality protein source forming the basis of a meal.
Action Items / Next Steps
- Ensure 75%+ of your protein is high-quality daily and in each meal.
- Build meals around lean meats, dairy, eggs, or high-quality plant proteins.
- If vegetarian/vegan, combine plant sources (e.g., rice + beans, quinoa, soy).
- Review your daily intake using a food tracker to check protein sources.