Nitrogen Balance: The Key To Muscle Growth

Any bodybuilder with a rudimentary understanding of the sport would know the key to gaining muscle is protein consumption. But how do we know if we are getting enough protein? You can find out here along with information on proteins and amino acids.

Any bodybuilder with a rudimentary understanding of the sport would know the key to gaining muscle is protein consumption. Granted, training, rest and other nutrients all enhance anabolism, and growth, but protein (being the key size-building nutrient) is absolutely essential when it comes to packing it on - 60-70% of bodily protein is found in muscle.

In fact, protein is the key "building" nutrient for a variety of bodily tissues, many of which support muscle growth (enzymes, skin, hair, nails, bones, and connective tissue are all constructed from protein). Protein makes up 15-20% of ones bodyweight and is thus, next to water, the body's second most abundant substance.

The inescapable fact remains: protein, and only protein, is the raw material from which muscle and many other bodily tissues are built. Proteins themselves are formed from amino acids, of which there are 20, comprised of both essential and non-essential.

Non-essential aminos can be produced by the liver. However, essential aminos must be made available through the diet before any muscle can be synthesized. Therefore, the correct ratios of essential and non-essential amino acids should be made available in sufficient quantities before any muscle can be produced.

Essential Amino Acids:

  • Histidine
  • Isoleucine
  • Leucine
  • Valine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan

Non Essential Amino Acids:

Obtaining the correct ratio of essential and non-essential amino acids involves eating complete protein sources such as eggs, meat and milk. As stated, protein is crucially important for muscle growth, it is however (at a more basic level), the building-block amino-acids that need to be in place, in the correct proportions, to ensure an optimal anabolic environment.

Eating sufficient complete proteins is the best way to achieve this, but how does one know if their diet is contributing to muscle growth, given compounding factors such as individual variability (processing rate of protein) and rest (protein synthesis occurs at this time), often serve to negate a supposed optimal protein intake.

Sources of complete proteins:

  • Egg whites
  • Turkey breast
  • Fish
  • Shellfish (shrimp, lobster, crab, clams, etc)
  • Chicken breast
  • Lean red meats (top round, lean sirloin, and flank)
  • Non-fat or low-fat dairy products
  • Protein powders (Whey protein, for example)

Nitrogen Balance

The good news, for those who are unsure as to whether they are getting sufficient protein, is protein status can be ascertained through nitrogen testing. What is nitrogen? Nitrogen is a compound unique to protein that can provide a direct measure of ones amino acid (protein) status. All macronutrients (protein, carbohydrates and fats) contain carbon, hydrogen and oxygen.

Among these, only protein contains the additional nitrogen molecule. Therefore, nitrogen excretion (meaning the amount of protein being eliminated from the body) can be measured to determine the amount of protein present in the body, and given up to 70% of protein is found in muscle tissue, this gives an excellent indication of the body's muscle building potential.

If the body is excreting more nitrogen than is being consumed, this sends out the warning signal that one should immediately increase their complete protein intake, to offset this nitrogen deficit.

In fact, nitrogen testing is the most widely accepted laboratory test used to determine the anabolic status of the body—it shows the body's nitrogen balance, or the extent to which the body is maintaining sufficient protein balance.

There Are Three Basic States Of Nitrogen Balance

  1. Positive: This is the optimal state for muscle growth—where the nitrogen intake is greater than nitrogen output. Essentially, it shows the body has sufficiently recovered from its last workout. The greater the nitrogen balance, the faster is workout recovery. This is the body's anabolic state.
  2. Negative: This is the worst state a bodybuilder can find themselves in—where nitrogen loss is greater than nitrogen intake. Not only is nitrogen drawn away from muscle, where it is needed for growth, it is also taken from the vital organs where serious damage can occur. Of course, negative nitrogen balance also destroys muscle and is consequently considered a catabolic state.
  3. Equilibrium: This state should be what a bodybuilder might achieve at the very minimum—where nitrogen intake and loss are equal. The trainer in this state is not regressing, nor are they really gaining any appreciable muscle.

How Nitrogen Is Measured

In scientific practice, initially nitrogen balance was tested for by carefully measuring the nitrogen content of foods. This content is then compared with the amount of nitrogen excreted.

The resulting value is the current nitrogen balance of this body. A simpler, more common, and exact, method involves measuring urine urea nitrogen loss—as 90% of nitrogen is lost through the urine, via the kidneys.

Whatever method is used, essentially ones nitrogen status is ascertained by measuring the amount of nitrogen in the diet minus the amount excreted over a 24-hour period.

How Negative Nitrogen Balance Can Occur: What To Watch For

  • As mentioned earlier, protein consumption is crucial are far as enhancing nitrogen balance is concerned. A negative nitrogen balance may result from consuming an insufficient amount of high biological value proteins, poor quality proteins (lunch meats, fatty meats, and vegetables for example), or protein sources lacking an optimal balance of the essential amino-acids.

    On a more serious level, a continued negative nitrogen balance will result in the body consuming its own blood products to support the internal organs.

    A severe lack of protein equates to fewer of the antibodies which are needed to fight infection—bacterial infections may result from this. The bloated stomach (seen in many third-world populations) ultimately results from the negative nitrogen imbalance induced bacterial infections, and death occurs soon after.

    Proteins importance, in this instance, is underscored by the fact that regardless how many nutrients are consumed at this point, death will occur if protein is not supplied.

  • Insufficient carbohydrate and fat consumption. To support protein synthesis, good quality fats and carbohydrates should be available for energy purposes. If one consumes primarily protein, without considering the importance of the other macronutrients, the body may metabolize protein for energy purposes, thus lowering the nitrogen balance—valuable amino acids will be shuttled to vital organs thus depriving the muscles of exactly what they need for growth.

  • Overtraining: Training involves breaking down muscle tissue. Protein and rest help to regenerate these tissues. Too much training, coupled with insufficient protein consumption will hasten a negative nitrogen balance.

    Following a training session, muscles soak up nutrients (including protein) like a sponge. If training is undertaken to frequently, these nutrients might eventually fall short of supporting continued growth.

How To Achieve A Positive Nitrogen Balance

Rule 1

The fundamental rule when aiming to increase nitrogen balance is to eat sufficient complete proteins.

Indeed, a caloric surplus of protein should be maintained at all times, to keep nitrogen balance positive. It is advisable to eat about six meals (each spaced two-three hours apart), each containing around 30-40-grams of protein, per-day.

The protein sources listed in this article are the most complete sources and should be eaten at each of these meals. Indeed, the idea is to continually increase the uptake of amino acids into the muscles. With this is mind, some key pointers can be followed:

  • To spare muscle protein breakdown during training, increase insulin (an anabolic hormone, which increases the uptake of amino acids and glucose into the muscle) by consuming a liquid meal containing protein and carbohydrates one-hour before training.
  • Immediately following training, consume the same protein/carbohydrate drink to saturate the muscles with amino-acids, and enhance protein synthesis.
  • Directly before bed, consume a drink containing both whey and a slow release protein like micellar casein, to tide the muscles over during this catabolic (fasting) period.

Rule 2

Achieve sufficient rest.

Resting the muscles following intense training is essential, if protein synthesis is to take place. If training sessions are too frequent, a protein surplus might be used to fuel training efforts, rather than maintaining a positive nitrogen balance.

Remember, if one finds themselves in a negative nitrogen balance, all training should be ceased and protein intake should be increased significantly. If training continues, muscle might continue to deteriorate.

Rule 3

Train in an anabolic fashion.

The idea when training to maximize positive nitrogen balance is to stimulate the greatest amount of fibers with the least amount of muscle break-down.

Upon finishing a training session, the muscles should be in an anabolic state, as this will accelerate a positive nitrogen balance. Long sessions usually leave the muscles exhausted in a negative way, and the body is left in a catabolic state as a result. Training in an anabolic fashion involves:

  • Training when the body is sufficiently rested from the last session - in other words, in a positive nitrogen balance.
  • Workouts should be kept short and intense—training duration between 30-45 minutes long, two-three exercises per body-part.
  • Train the body again, only when it has been rested.

Dorian Yates blood and guts and Mike Mentzers heavy duty training styles tended to replicate this anabolic method, and if these guys results are anything to go by, they certainly achieved a positive nitrogen balance.

The general rule, in terms of protein intake for size gains has, for some time, been one-gram of protein per pound of bodyweight. Certainly, the recommended daily allowance (RDA), for the general population, of 0.8 grams per kilogram of bodyweight is way off the mark for bodybuilders and other strength athletes.

A nitrogen balance study of bodybuilders demonstrated an increased protein need relative to controls and estimated the RDA for bodybuilders to be 1.7 g/kg total.

In another study, impressive strength gains of 5% and size of 6% were seen over several months of strength training in world-class weight lifters when they increased their dietary protein from 1.8 to 3.5 g/kg of body weight per day.

Both these studies underscore the greater need among strength athletes, for a higher protein consumption. For the average, non-pro, bodybuilder, it is best to err on the side of caution and consume more than the one-gram-per-pound guideline, to ensure maximal nitrogen retention.


A fundamental prerequisite of any bodybuilding program, is a sufficient intake of complete proteins. A positive nitrogen balance is an accurate indication that one is consuming adequate protein.

Indeed, keeping the muscles saturated in nitrogen, given this is a direct measure of protein status, is arguably the single most important variable a bodybuilder can assess. Follow the guidelines in this article to offset the dreaded negative nitrogen balance, and grow.