1.6 or 3.2 G/Kg of Protein per Day for Muscle & Strength?

Eating enough protein is one of the most enjoyable things you can do to improve your muscle growth and strength gain.

But how much protein is enough?

A new study compared intakes of 1.6 and 3.2 grams of protein per kilo of bodyweight in 48 resistance-trained men over a 16-week training program.¹

There were no significant differences in strength or muscle gains between groups, indicating that 1.6 grams of protein per kilo bodyweight was sufficient to maximize results from their training.

This is in line with a previous meta-analysis of 49 strength training studies that also found 1.6 g/kg to be sufficient to optimize results.²

While there are circumstances where more protein is beneficial, 1.6 g/kg is enough for most of us, most of the time.

When Do You Need More Protein?

So, what are some circumstances in which you might need even more protein?

Here are some examples:

• You are in a caloric deficit.
• You are training a lot (more than “normal”)
• You already have a low body fat percentage and/or are very muscular.
• You are cutting to lose weight and keep your muscle.
• You are injured.

A prime example of someone who might need a lot more protein than a regular person is someone who is cutting for a bodybuilding show.

That person is likely (or hopefully) already very muscular and in a caloric deficit. In this case, eating upwards of 3 g/kg of protein per day may very well be necessary to minimize muscle loss.³

We might also need more protein as we age. Or, at least a lack of protein might accelerate our age-related muscle loss.

If you are trying to build muscle after 50, it’s a good idea to keep an extra eye on your daily protein intake to ensure you are getting at least 1.6 grams per kilogram a day.

It should also be noted that the number 1.6 g/kg is the mean optimal intake. In one study on eight natural bodybuilders, their mean daily protein requirement to not lose muscle mass was 1.7 g/kg. Still, the 95% confidence interval (the number that theoretically would cover the protein needs of 95% of people with similar circumstances, i.e., muscularity, body fat, training routine, etc.) was 2.2 g/kg.⁴

Do you want to calculate how much protein you need for optimal muscle growth or fat loss?

Use our protein calculator.

Want to increase your protein intake but don’t know what to eat?

Check out our list of the best protein foods.

References

1. Effects of 16 weeks of two different high-protein diets with either resistance or concurrent training on body composition, muscular strength and performance, and markers of liver and kidney function in resistance-trained males. J Int Soc Sports Nutr. 2023 Dec;20(1):2236053.
2. 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. Br J Sports Med. 2018 Mar;52(6):376-384.
3. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014 May 12:11:20.
4. 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. J Nutr. 2017 May;147(5):850-857.