Protein and Strength Training: How Much is Too Much?

Protein is the major functional and structural component of every cell in the body.  All enzymes, membrane carriers, blood transport molecules, intracellular matrices, hair, fingernails, serum albumin, keratin, and collagen are proteins, as are hormones and a large part of membranes.  Bottom line, they are important!!  The recommended daily allowance (RDA) for protein for adults ages 18 and up is 0.8g per kilogram of body weight per day, and should contribute 10 to 35% of the total kilocalories consumed per day.  This means an adult weighing 150 lbs (~68.2 kg) should be consuming around 55g of protein per day.  OK, but how does this exchange into servings of food?  Let's break it down:

Meat, Fish, Chicken, Seafood: 7 grams per ounce
Eggs: 7 grams per egg
Milk, Yogurt: 8 grams per cup
Legumes: 7 grams per 1/2 cup
Cottage Cheese: 10-12 grams per 1/2 cup
Cheese: 7 grams per ounce

But what about strength training?  Clearly, the protein needs for athletes engaged in strength training are increased, but how much is actually needed?  Most studies suggest that the protein requirement in strength and power athletes is about 1.4 to 1.75g per kilogram body weight, or approximately 100% higher than the RDA for adults.  Given the high energy intakes required by these athletes, the protein requirement is still below 20% of their total kilocalorie intake per day.  So lets take that same adult weighing 150 lbs (~68.2 kg), and that individual has now begun a rigorous strength training program.  The amount of protein needed per day has increased from 55g to between 96 and 119g.  That is about 40 to 60g of extra protein needed per day.  This may seem like a high number, but lets look at the break down above.  It can be easily achieved by adding an extra 2 cups of milk and 4 ounces of cheese per day to that individuals diet.
 
So what happens if an athlete engaged in strength training decides to add additional protein above the recommended 1.4 to 1.75g per kilogram on a daily basis?  The additional protein will go straight to their lean muscle and make them look like the Incredible Hulk faster, right?  WRONG!!  So what really happens?

 In our bodies, there is no real "storage" of proteins, all proteins are "functional".  This means that our bodies use the proteins we need and there is no opportunity to store them for later.  Therefore, all of the extra protein we eat (more than the RDA for adults, in other words), needs to be dealt with.  Our bodies have extensive metabolic processes that break down the protein into individual amino acids and strip the Nitrogen from each amino acid,  leaving a carbon skeleton of sorts.  And what do you think our bodies do with these carbon skeletons?  Turn them into fat cells, of course!   

Eating an excess amount of protein is also hard on an individuals kidneys.  This is because, as stated above, our bodies need to strip the Nitrogen from the amino acid and get rid of it somehow, because that Nitrogen is toxic to us.  That Nitrogen is made into urea and sent to the kidneys to be eliminated via urine after an extensive filtering process.  An excess amount of urea for our kidneys to filter is very strenuous on them.  Think about those individuals with progressive kidney failure, or are in any stage of kidney disease.  Studies have shown that when these individuals are fed a higher protein intake their kidney function deteriorates more rapidly.  I know what your saying: I DON'T have progressive kidney failure or kidney disease...my kidneys are healthy!  These studies just prove that a higher intake of protein can translate into a higher workload for the kidneys.

So when beginning a strength training regimen, please keep in mind that eating a high protein diet may not be doing what you think in your body.  Instead of going straight to your lean muscle tissue, it is probably going straight to your thighs and gut!