Protein Intake: How Much Protein Should You Eat per Day?

Key Points:

  • If you lift weights, your daily protein requirement rises. In the short term, this happens because your body needs more protein to repair itself after training. In the long term, it is because you need more protein to maintain your larger muscle mass.
  • The recommended dietary allowance (RDA) of protein is 0.8 g/kg bodyweight/day (g/kg/d). This intake is sufficient to maintain health and muscle mass in a non-training population.
  • If you are training to increase your strength and muscle mass, you are recommended a daily intake of 1.4–2.2 g/kg/d to maximize your gains.
  • A caloric deficit increases your protein needs further, and you can decrease your risk of muscle loss during a cut by increasing your protein intake by an additional 0.5 g/kg/d.
  • You can calculate your daily protein need with our protein calculator.

Protein is the building blocks of your body. Your hair, skin, hormones, blood, bones and – last but not least – muscles are all built from these chains of amino acids.

Today, it is well-established that increasing your protein intake from an average to optimal level can bring substantial extra gains from training. A 2018 systematic review and meta-analysis of 49 training studies found that participants who increased their daily protein intake from an average of 1.4 g/kg to 1.8 g/kg built 27% more fat-free mass and gained 9% more strength over 2–3 months than their counterparts in the control groups.1 For participants who had already trained for several years before the studies began, the effect of extra protein was even larger.

How Much Protein Do You Need?

If you don’t care about the details and just want to know how much protein you should eat, go ahead and use our protein calculator here. Otherwise, read on.

A number of previous studies, summarized in a report from the World Health Organization, have found that healthy adults on average needs to consume a minimum of 0.6 g protein per day if they are to avoid adverse health effects.2 However, that’s on average, meaning it is only enough for about 50% of the population. The amount of protein that seems to be enough for 97.5% of the population is instead 0.8 g/kg/day.

This is the minimum intake necessary to avoid protein loss in your body. Which, as mentioned, isn’t only used to build your muscles, but in a majority of vital body functions and organs. But minimum isn’t the same as optimal. If you want to eat enough to support the most gains from your current training program, how much protein do you need?

Daily Protein Intake for Bodybuilders and Lifters

A systematic review on protein and exercise from the International Society of Sports Nutrition concluded that an overall daily protein intake in the range of 1.4–2.0 g/kg/d is sufficient for most exercising individuals looking to build muscle mass and strength, and improve their body composition.3

The previously mentioned meta-analysis of 49 training studies found that increasing the protein intake from 1.4 to 1.8 g/kg/d led to 27% greater muscle growth and 9% greater strength gains over the course of 2–3 months. These gains were even greater in those of the participants who already had strength trained for several years. Another finding of this analysis was that the level of protein intake where additional protein didn’t result in additional significant gains was on average 1.6 g/kg/d. Once again: that’s on average. The level of protein intake that was found to be sufficient for 97.5% of all the 1 863 participants in the analysis was 2.2 g/kg/d.

Another study, using natural bodybuilders as subjects, came to similar conclusions.4 Using a method to measure the rate of protein oxidation in response to different levels of protein intake, the researchers could conclude that these eight muscular men needed at least 1.7 g/kg/d on average not to lose any fat-free mass. Worth noting is that the measurements were conducted on a rest day, and training increases your protein requirements during the following 24 hours or so. Finally, in similarity to the previously mentioned meta-analysis, the protein intake required to maintain muscle mass in 97.5% of men with similar levels of muscle mass was calculated to 2.2 g/kg/d. The men in this study had a fat-free mass index (FFMI) of 24, which probably places them among the top 1% most muscular men in the population, if not higher.

Factors That Increase Your Protein Need

There are primarily three major factors that increase your protein need that you should know about:

  • Exercise increases your protein need both in the short and long term. In the short term, you require some extra protein the day or two after a hard workout to repair your body. In the long term, as you build up more muscle mass over the years you will require more protein to maintain that mass.
  • A caloric deficit will increase your muscle breakdown. One way to counter this is by increasing your protein intake. Adding about 0.5 g protein/kg/d when you are in a caloric deficit will generally put you in the right ballpark. If you are both muscular and already at a low body-fat percentage, a protein intake upwards of 2.7–3.1 g/kg/d has been recommended in the scientific literature for maintaining muscle mass during a cut.5 6
  • Aging decreases your anabolic response to protein, meaning that as you get older, the amount of protein needed to maximize your muscle growth increases, both per meal and in terms of your total daily intake. “Older” in this case means about 60 years or so. How much extra protein? Science has yet to map this out, but if you stick to the higher ranges of the intervals mentioned in this article, you are probably covered. You can read a lot more about this in our article Building Muscle as You Age: Protein Needs for the Older Lifter.

Note that it is primarily your fat-free mass that dictates your protein need. The recommendations in this article are generally based on studies of normal-weight participants, which means that if you are very overweight or obese you might have to modify them slightly. One rule of thumb for doing that is to make a general estimate of what would constitute a “normal weight” for you and calculate your protein need based on that figure.

Is a High Protein Diet Bad For Your Kidneys?

There is no evidence of an upper limit where a high protein intake has adverse health effects for healthy adults, including effects on the kidneys.7 8

One recent study had 14 healthy, strength-training men eat an average of 3 g protein/kg/d for a year, with no adverse effects on blood fat, kidney, or liver function.9

In Conclusion

Here are the key take-aways from this article.

  • If you are strength training regularly and eating in a caloric balance, you need about 1.6–2.2 g protein/kg/day to maximize your muscle growth and strength gains. If you are in a caloric deficit, this number increases by about 0.5 g/kg/d.
  • If you are new to strength training, then your protein need is lower, and you could stick to the lower end of the interval. If you have trained for several years and have built up a large muscle mass, then you could stick to the higher end of the interval.
  • If you are 60 years old or more, sticking to the higher end of the interval might be necessary to maximize your muscle growth.

The most important thing for building muscle and getting stronger is without a doubt good training. But if you’ve already got your training in place, you might be able to maximize your results from it by eating a little more protein than you normally would.

I hope you learned something from this article. If you would like to read more about protein, check out our other articles:

References

  1. Br J Sports Med. 2018 Mar;52(6):376-384. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults.
  2. Protein and amino acid requirements in human nutrition. Report of a joint FAO/WHO/UNU expert consultation (WHO Technical Report Series 935). 2007.
  3. J Int Soc Sports Nutr. 2017 Jun 20;14:20. International Society of Sports Nutrition Position Stand: protein and exercise.
  4. J Nutr. 2017 May;147(5):850-857. Indicator Amino Acid-Derived Estimate of Dietary Protein Requirement for Male Bodybuilders on a Nontraining Day Is Several-Fold Greater than the Current Recommended Dietary Allowance.
  5. J Sports Sci. 2011;29 Suppl 1:S29-38. Dietary protein for athletes: from requirements to optimum adaptation.
  6. J Int Soc Sports Nutr. 2014 May 12;11:20. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation.
  7. Nutr Metab (Lond) 2, 25 (2005). Dietary protein intake and renal function.
  8. Int J Sport Nutr Exerc Metab. 2000 Mar;10(1):28-38. Do regular high protein diets have potential health risks on kidney function in athletes?
  9. Journal of Nutrition and Metabolism, vol. 2016, Article ID 9104792. A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males.