Thirty grams is not an absorption ceiling
Your digestive system can digest and absorb much more than 30 g of protein in a meal. The more useful question is how much protein in a meal maximizes the muscle-protein-synthesis response in a given context.
A practical heuristic
For trained adults, roughly 0.4 g/kg per meal across several meals is a reasonable planning target when total daily intake is around 1.6 g/kg/day. Larger meals are not “wasted”; amino acids can be used for other tissues and metabolic purposes.
Evidence notes
- Schoenfeld & Aragon review: ~0.4 g/kg/meal across at least four meals is a practical per-meal target when aiming for ~1.6 g/kg/day, not an absorption ceiling. PubMed: https://pubmed.ncbi.nlm.nih.gov/29497353/
- Moore et al. acute post-exercise study in young men found ~20 g high-quality protein maximized MPS in that specific protocol; this does not establish a universal 20–30 g whole-body absorption limit. PubMed: https://pubmed.ncbi.nlm.nih.gov/19056590/