How much protein per muscle mass?

Question

Earlier topics such as Protein: How much is too much? acknowledge body mass but not muscle mass. I want to steer attention from recommendations in terms of body mass to muscle mass.

I cannot understand figures such as 1.5-2grams protein per each kilogram in your body. Suppose twin bodybuilders/crossfiters A and B with the same physical profile except differences in the amount of muscles and fat. Suppose a guy A with 90kg weight and 30kg muscle mass. Suppose a guy B with 70kg weight and 35kg muscle mass. I cannot understand why A should take more protein (i.e. 90*2=180grams) than B (i.e. 70*2=140grams)

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where B being a guy with 7-8% fat body percentage requires far less protein than the guy A with 20-30% fat body percentage. My pre-assumption was that more muscle requires far more maintenance so B should take more protein than A in order to maximise muscle growth and keep the metabolism with a lot of muscles running.

I am very skeptical with statements that suggest to take protein according to body mass. I find that muscle mass is far more important to protein synthesis than the mass containing muscle mass, fat mass, liquids and bones. So

1. How much protein per muscle mass?

2. Why is protein usually suggested in terms of body mass and not in terms of muscle mass? (there are tools today to find the body profile with muscle mass and fat mass precisely enough)

Answer 1

There are a couple articles I can recommend, one is a nice summary article by Greg Nuckols and a more in-depth article by the Examine.com guys.

You'll still see recommendations in terms of body mass--or technically speaking desired body mass. Greg Nuckols recommends .82g / lb or 1.8g / kg body weight based on studies sited in this article. The examine.com guys have a range:

• .5 g / kg is the USRDA and is the absolute minimum you should consider (keeps you alive and in general health but that's about it)
• .5-1g / kg is for people new to exercise and more health conscious. Works for the initial stages of building muscle.
• 1-1.5g / kg is for people working to build muscle and reaching athletic goals
• 1.5-2.2g / kg is a very under-researched recommendation based on anecdotal evidence--examine.com does not recommend going over 1.8g/kg.

One of the problems of recommending protein ratios off of lean mass is the difficulty of measuring the lean mass. Even more so if we are talking muscle mass specifically. Bio-impedance scales can have as much as 2% variance in it's measurements day to day--there is no way someone looses or gains that much lean mass or muscle mass that quickly. That's why the ratios are usually for overall body mass. Also note, if your goal is a change in body composition, the protein intake should be based on your target body mass.

So what happens to excess protein? The rates of protein synthesis and breakdown increase at the same rate--so your body simply doesn't use the excess protein. The major caveat is that you are not taking anything that alters your body's rate of protein synthesis such as steroids.