Many people, including some researchers, have differing opinions when it comes to the amount of daily protein your body actually needs. The numbers also vary depending on whether you’re a strength or an endurance athlete. Additional factors like age and the number of days you’re hitting the gym will also play a role in your intake.
Do you need the suggested RDA of 0.8 grams/kg/day or is it more in line with 1-2 gram/kg/day? The answer may depend partly on the volume of work you’re doing in daily workouts. Here is what some of the research has shown regarding daily protein intake.
Research Shows a Higher Need for Protein Intake
Back in the 1970’s and 1980’s, a few published studies suggested exercise might actually cause significant changes in protein metabolism. One such study done at the USDA HNRC on Aging at Tufts University in 1988. I was actually one of the ‘”young” research subject for this particular study. The study by Meredith and colleagues looked at the protein needs of six young (26.8 +/- 1.2 yr) and six middle-aged (52.0 +/- 1.9 year) endurance-trained men. All of the subjects consumed either 0.6, 0.9, or 1.2 grams/kg/day of high-quality protein over three separate 10-day periods. All subjects maintained their training and a constant body weight. The results of the study estimated that protein requirement was 0.94 +/- 0.05 grams/kg/day for the 12 men, with no effect of age. The data from this study showed greater daily protein needs than the current Recommended Dietary Allowance of 0.8 g/kg/day.
Additional Research on Daily Protein
Several studies based on data collected from individuals engaged in vigorous aerobic exercise, on a regular basis, demonstrated higher daily protein needs more in line with 1.1 to 1.4 grams/kg/day. This by the way is about 38%-75% above the current RDA range. Various research groups have reported the optimal intake should be more in line with a protein range of 1.5 to 1.8 grams/kg/day; about 88% to 125% above the RDA.
A research paper published by Roger Fielding and his colleague cited “current recommended intakes of daily protein for strength and endurance athletes are 1.6 to 1.7 g/kg and 1.2 to 1.4 g/kg per day, respectively. They went on to mention that most athletes get enough protein in their diet. Where most typically get things wrong is with “the timing and nutritional content of the post-exercise meal, (is) often overlooked.”
Protein Recommendations
Current recommended protein intake could actually limit muscle growth. Dietary protein needs according to Lemon and colleagues, for physically active individuals, has been debated for centuries. The RDA guidelines are not going to change any time soon. The evidence supports a higher daily protein intake for individuals involved in strenuous physical activity, such as strength training. More in line with 1.1 to 1.8 grams/kg/day, in order to effectively increase lean muscle tissue. If you are not involved in regular exercise, the RDA of 0.8 grams/kg/day will suffice.
References
1. Lemon, PWR (2000). Protein metabolism during exercise. Exercise and Sport Science, 19-27.
2. Evans WJ et al. (1983). Protein metabolism and endurance exercise Phys Sports Med 11:63-72.
3. Friedman JE et al. (1989). Effect of chronic endurance exercise on the retention of dietary protein. Int J Sports Med 10:118-123.
4. Tarnoplosky MA (1992) et al. Evaluation of protein requirements for trained strength athletes. J Applied Physiology 73:1986-1995.
5. Lemon PWR, Tarnoplosky MA et al. (1992). Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. J Applied Physiology 73:767-775.
6. Fielding, R, et al. (2002). What are the dietary protein requirements of physically active individuals? New evidence on the effects of exercise on protein utilization during post-exercise recovery. Nutr Clin Care, 5(4):191-6.
