Deep Dive: Protein Requirements for Older Adults — The Research¶

Reading time: ~10 minutes
Prerequisite: Chapter 2.7 (Nutrition for Longevity)

The Big Picture¶

The standard RDA for protein (0.8 g/kg body weight) was established to prevent deficiency in the general population. But preventing deficiency isn't the same as optimizing health—especially for older adults trying to maintain muscle mass.

Recent research suggests older adults need significantly more protein than the RDA. This deep dive covers the evidence.

Why Older Adults Need More¶

Anabolic Resistance¶

As we age, our muscles become less responsive to protein. This is called "anabolic resistance."

What happens: A young adult might need 20g of protein at a meal to maximally stimulate muscle protein synthesis (MPS). An older adult might need 30-40g for the same effect.

Why it happens:
- Reduced muscle blood flow
- Blunted mTOR signaling
- Chronic low-grade inflammation
- Changes in hormone levels

The practical implication: Older adults need to eat more protein per meal to get the same muscle-building response.

The Research Numbers¶

Total Daily Protein¶

A 2025 study using tracer methods directly measured protein needs in sarcopenic older adults:
- Estimated average requirement: 1.21 g/kg/day
- Recommended intake: 1.54 g/kg/day

These numbers are nearly double the RDA.¹

In practical terms: For a 150-pound person (68 kg), that's approximately 82-105 grams of protein daily, compared to the RDA of about 55 grams.

Observational Support¶

A 2025 analysis found that older adults who met recommended intakes (1.0-1.5 g/kg/day) had:
- Significantly higher muscle mass (OR ≈ 2.16)
- Higher strength (OR ≈ 2.31)

compared to those who didn't meet recommendations.²

Per-Meal Distribution¶

Total daily protein matters, but distribution across meals may matter just as much.

The "Muscle Full" Effect¶

There's a limit to how much protein your muscles can use at one meal. Eating 80g at dinner doesn't provide 4x the benefit of eating 20g.

The Research¶

A 2014 study found that even distribution (30g at breakfast, lunch, and dinner) increased 24-hour muscle protein synthesis by approximately 25% compared to the typical pattern (10g breakfast, 15g lunch, 65g dinner)—even when total daily protein was identical.³

Per-Meal Targets¶

The Leucine Threshold¶

Leucine is the amino acid that most strongly triggers muscle protein synthesis. It's the "signal" that tells muscles to start building.

Leucine Requirements¶

Leucine Content of Foods¶

Key insight: Animal proteins are more leucine-dense than plant proteins. Plant-based eaters may need larger portions or strategic combinations.

Protein Quality¶

Not all protein sources stimulate MPS equally.

The DIAAS Score¶

DIAAS (Digestible Indispensable Amino Acid Score) measures protein quality based on:
1. Amino acid profile (does it have all essential amino acids?)
2. Digestibility (how much can your body actually absorb?)

What this means: You need about 20-30% more plant protein to achieve the same MPS as animal protein.

Plant-Based Considerations¶

Plant-based eating is compatible with adequate protein for longevity, but requires more intentionality.

Challenges¶

1. Lower leucine content: Most plant proteins have 30-50% less leucine per gram
2. Lower digestibility: Plant proteins are 5-15% less digestible
3. Incomplete amino acids: Some plants are low in certain essential amino acids

Solutions¶

1. Eat more total protein: Target 1.3-1.6 g/kg instead of 1.0-1.2 g/kg
2. Prioritize soy: Tofu, tempeh, and edamame have the highest plant leucine content
3. Combine proteins: Beans + grains provides all essential amino acids
4. Consider leucine supplementation: 2-3g leucine added to meals may help

Practical target: A plant-based older adult might need 40-50g of plant protein per meal to achieve the same muscle protein synthesis stimulus as 30g of animal protein.

The Breakfast Problem¶

Most people eat their smallest protein dose at breakfast.

Typical Pattern¶

Why Breakfast Matters¶

Breakfast follows the longest fast of the day (overnight). This is when your muscles are most catabolic (breaking down). Protein at breakfast can stop this breakdown and kickstart synthesis.

High-Protein Breakfast Ideas (30+ grams)¶

Collagen: A Special Case¶

Collagen supplements are popular, but they don't effectively trigger muscle protein synthesis.

Why: Collagen is low in leucine and lacks some essential amino acids.

What collagen IS good for: Connective tissue support (skin, joints, tendons)

The recommendation: Don't count collagen toward your protein targets. Consider it supplemental.

Practical Takeaways¶

For coaches, here's what matters:

1. Palm-sized portion at each meal: About 25-35g of protein
2. Breakfast protein is critical: Most clients under-eat protein at breakfast
3. Spread it out: Even distribution beats back-loading
4. Plant-based requires more: 20-30% larger portions needed
5. Quality matters: Animal proteins are more efficient, but plant proteins work with planning

References¶

1. Wu H, et al. Dietary protein requirements of older adults with sarcopenia. Frontiers in Nutrition. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC11906324

2. Lee E, Kim I, Lim S. Physical activity and protein-intake strategies to prevent sarcopenia in older people. International Health. 2025;17(4):423-430. doi:10.1093/inthealth/ihae064

3. Mamerow MM, et al. Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. The Journal of Nutrition. 2014;144(6):876-880. doi:10.3945/jn.113.185280

4. Coelho-Júnior HJ, et al. Protein intake and physical function in older adults: A systematic review and meta-analysis. Ageing Research Reviews. 2022;81:101731. doi:10.1016/j.arr.2022.101731

Return to Chapter 2.7: Nutrition for Longevity