By Joseph Scherger, MD, MPH

Vice President, Primary Care, Eisenhower Medical Center; Clinical Professor, Keck School of Medicine, University of Southern California, Los Angeles

Dr. Scherger reports no financial relationships relevant to this field of study.

SYNOPSIS: The timing of protein intake during or between meals does not play a role in anabolic response, muscle strength, or functional outcomes.

SOURCE: Kim IY, et al. Protein intake distribution pattern does not affect anabolic response, lean body mass, muscle strength or function over 8 weeks in older adults: A randomized-controlled trial. Clin Nutr 2018;37:488-493.

A team of researchers at the University of Arkansas conducted studies on whether the timing of protein intake affects muscle strength, mass, or function. In another randomized, controlled trial conducted in 2015, Kim et al found no differences in the anabolic response to differing patterns of protein intake during a day, but the quantity and quality of protein were important.1

This 2018 study took place over an eight-week period to see if there were any anabolic differences based on protein timing. The authors found none. In a 2016 study, again conducted by these same investigators, similar results occurred in healthy young adults.2 The sample size in this 2018 eight-week study was small — 14 adults randomized to two groups of seven. One group consumed most dietary protein with dinner, while the other group consumed dietary protein evenly throughout the day. Lean body mass, whole body protein kinetics, and muscle protein fractional synthesis rate were measured in both groups. The authors observed no differences.

COMMENTARY

Nutrition is a neglected area of medicine in the United States. However, when experts consider nutrition, recommendations often are too complicated to be practical. One such complexity, often used in adults relative to exercise, is the timing of protein intake. The work by Kim et al helps simplify nutrition recommendations. Protein intake is important, including the quality of the protein, but protein timing is of no value.

Racing to eat a high-protein bar or shake after exercise is not necessary. Keep adequate protein on hand, and good muscle mass and function will follow.

REFERENCES

  1. Kim IY, et al. Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults. Am J Physiol Endocrinol Metab 2015;308:E21-E28.
  2. Kim IY, et al. The anabolic response to a meal containing different amounts of protein is not limited by the maximal stimulation of protein synthesis in healthy young adults. Am J Physiol Endocrinol Metab 2016;310:E73-E80.