Population studies have found that failing to meet the recommended daily intake of protein

is correlated with lower lean body mass, and those exceeding the RDA associated with

significantly greater lean body mass compared to those failing to meet the recommended intake.

Greater protein intake has also been linked to greater grip strength over time, though not

considered enough to be clinically meaningful.

You don't know if these correlations or even cause and effect, though, until you put it to

the test. To see if increasing the protein intake for the elderly would help, Harvard researchers

randomized older men with moderately impaired function to control diets, offering the recommended

0.8 grams per kilogram of body weight per day, or bumping them up to 1.3 grams per kilogram

a day with a weigh and casein protein

powder with or without added testosterone.

Six months later, there was no difference in lean mass, muscle strength, fatigue, walking

speed, stair climbing power, or any of the other measures of performance, function or well-being

with the added protein, whether combined with testosterone or not, suggesting that the recommended

daily allowance of 0.8 grams of protein per healthy kilogram of body weight, or about 50 grams

a day, is sufficient to maintain lean body mass even in old age and does not support this thought

that adding extra protein could promote bulking up additional lean mass.

Even in studies that do show an increase in lean mass with protein supplementation doesn't

necessarily mean an increase in muscle mass.

The field is said to be plagued,

with researchers referring to lean mass as an indication of muscle mass.

But high protein intake alone can cause significant liver and kidney swelling,

...