Is Nitrogen Balance the Key to Building Muscle? What 14 Studies Say

Key Takeaways

Nitrogen balance is a measurement of the total amount of nitrogen you consume versus the total amount of nitrogen you excrete (primarily in urine), and it’s used by researchers to estimate whether you’re gaining or losing muscle mass.
Nitrogen balance is a poor predictor of your ability to build muscle and you can’t directly control it, so it’s not worth worrying about.
Keep reading to learn what science says about nitrogen balance and muscle growth, and what you should focus on instead!

If you look online for how to build muscle and lose fat, here’s the most common answer you’ll find:

If you want to build muscle, you have to eat more calories than you burn over time. This will result in muscle growth and a bit of fat gain.

If you want to lose fat, you have to eat fewer calories than you burn over time. This will result in fat loss, but if you play your cards right, you’ll hold onto most of your muscle. 

And by and large, this is true.

Except when you’re a newbie (roughly your first year of so of proper weightlifting), you’re going to make the most progress by alternating between “lean bulking” and “cutting” phases—building a bit of muscle while accepting a slight bump in body fat, and then “cutting” off the fat while retaining the newly-built muscle. 

Recently, though, you may have heard that you can build muscle and lose fat simultaneously if you maintain a positive nitrogen balance

According to proponents of this idea, you can build muscle just as effectively while cutting as you can while bulking, so long as you stay in positive nitrogen balance. 

What is a positive nitrogen balance, and can it help you “recomp” the way these people claim? 

Keep reading to find out. 

What Is Positive Nitrogen Balance?

factors affecting nitrogen balance


Before you can understand what positive nitrogen balance means, you have to understand what nitrogen balance means.

First, nitrogen is a colorless, odorless gas that makes up about three-quarters of Earth’s atmosphere, and it’s found in all living things from bacteria to plants to people. Specifically, nitrogen is a key component of amino acids, which are the “building blocks” of protein. 

Nitrogen balance is a measurement of the total amount of nitrogen you consume versus the total amount of nitrogen you excrete (primarily in urine). As protein is the primary storage site of nitrogen in the body and source of nitrogen in the diet, nitrogen balance is sometimes used by researchers as a proxy for your total body protein stores. 

In a way, the concept of nitrogen balance is very similar to the idea of energy balance. Energy balance is simply the relationship between how many calories you consume versus how many you expend, and nitrogen balance is the relationship between how much nitrogen you consume and excrete. 

If you’re in positive nitrogen balance, it means you’re consuming more nitrogen than you’re excreting. 
If you’re in negative nitrogen balance, it means you’re excreting more nitrogen than you’re consuming.
And if you’re in neutral nitrogen balance, it means you’re consuming and excreting roughly the same amount of nitrogen. 

Summary: Nitrogen balance refers to the relationship between how much nitrogen you’re consuming (mostly in the form of dietary protein) and excreting (primarily through urine), and positive nitrogen balance refers to a state where you’re consuming more nitrogen than you’re excreting.

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Is Positive Nitrogen Balance Important for Building Muscle?

For many years, scientists have used nitrogen balance to estimate whether or not someone is gaining or losing muscle mass.

The thinking goes that since muscle mass is rich in nitrogen, a change in your nitrogen balance indicates whether you’re gaining or losing muscle. If you’re in negative nitrogen balance, it’s a sign your body is breaking down muscle tissue; and if you’re in positive nitrogen balance, it’s a sign you’re building muscle. 

And this is true as far as it goes: usually, if someone is in positive nitrogen balance, they’re gaining muscle, and if they’re in negative nitrogen balance, they’re losing it.

Although nitrogen balance is helpful in this regard, it’s not a great measure of whether you’re gaining, losing, or maintaining muscle mass. 

Most of the studies on nitrogen balance have only measured total body nitrogen balance, whereas what you should really care about is how much nitrogen is being added to or taken from your skeletal muscle tissue. 

All tissues in the body contain nitrogen and can thus affect your nitrogen balance. Seeing as skeletal muscle mass only makes up about 30 to 40% of your body weight, changes in your nitrogen balance could be entirely due to gaining or excreting nitrogen from other tissues.

For example, studies have shown that you can be in positive nitrogen balance and still lose muscle. Other research has shown that if you try to predict how much muscle someone will build based on their nitrogen balance, you’ll probably overestimate their potential muscle gain many times over.

In other words, the relationship between nitrogen balance and muscle gain or loss is similar to the relationship between your car’s speed and fuel consumption. While you’ll generally use more fuel the faster you go—the two values are loosely related—there are many other factors that can affect this relationship.

Things like rough or steep terrain, a headwind, or a heavy load will increase your fuel consumption regardless of your speed, and things like downhill terrain, a tailwind, or drafting behind another car will reduce your fuel consumption.

In the same way, many other organs in the body such as the liver, kidneys, and intestines absorb and release nitrogen, which can affect your nitrogen balance without affecting your muscle mass. 

This is why scientists now usually rely on other methods of measuring muscle gain or loss, such as measuring muscle protein synthesis

So, circling back to our original question, is nitrogen balance important for building muscle? 

Yes and no. 

If you’re in positive or neutral nitrogen balance, you’re probably able to at least maintain if not gain some muscle. Where people go wrong is thinking that nitrogen balance is a causative factor you can control to increase muscle growth. It isn’t. 

In reality, your nitrogen balance is the result of your diet, training, and other lifestyle factors that lead to muscle growth.  

The bottom line is there are no special “hacks” you can use to boost your nitrogen balance aside from all of the things you’ve probably heard are important for building muscle: 

If you do these things, nitrogen balance will take care of itself. 

Summary: Although positive nitrogen balance and muscle gain are loosely related, it’s not a great measure of whether or not you’re gaining muscle, and isn’t something you can directly control.

Can a Positive Nitrogen Balance Help You “Recomp?”

positive nitrogen balance diet

Some people say that if you maintain a positive nitrogen balance, you can gain muscle just as effectively while in a calorie deficit as you can while in a calorie surplus, or achieve body recomposition, as it’s known.  

Once again, though, these people are confusing the map for the territory. 

While body recomposition is absolutely possible—the degree to which you can achieve it depends primarily on how long you’ve been weightlifting. 

You can achieve impressive body recomposition when you’re new to weightlifting, but your ability to “recomp” grows smaller and smaller as you approach your genetic potential for muscle gain

Read: An Easy and Accurate Way to Measure Your Body Composition

As Dr. Eric Helms, a member of Legion’s Scientific Advisory Board, puts it,  “ . . . highly trained bodybuilders who achieve a great deal of muscularity may not make measurable improvements in muscle mass even over the course of a six month period.”

And what if you maintain a positive nitrogen balance despite maintaining a calorie deficit? 

Well, science says this is basically impossible for anyone but newbies. 

If you’re pretty lean already and/or close to your genetic limit for muscle gain, your chances of maintaining a positive nitrogen balance while getting even leaner are basically zero. Just about every natural weightlifter who’s lean (<15/25% body fat for men/women) and has a decent amount of muscle is going to spend a good deal of time in negative nitrogen balance while trying to get down to very low body fat percentages (<10/20% or so). 

Ironically, although some fitness gurus claim that you can build muscle regardless of your calorie intake as long as you’re in positive nitrogen balance, one of the most important variables that affects your nitrogen balance is your calorie intake

In other words, if you’re in a calorie deficit, you’re probably in negative nitrogen balance, and vice versa (assuming you also eat enough protein). 

All in all, saying you can gain muscle while losing fat by maintaining positive nitrogen balance is like saying you can spend as much money as you want as long as you don’t get into debt—it’s classic circular reasoning.

Nitrogen balance simply describes what’s going on in your body and how well your diet and training are working—it’s not some switch you can flip to build muscle and lose fat regardless of your diet and training. 

At bottom, nitrogen balance is a relatively pointless thing to focus on if you just want to get bigger, leaner, and stronger.

Summary: Nitrogen balance isn’t a “hack” for gaining muscle and losing fat at the same time. Unless you’re new to proper weightlifting, you’ll almost certainly be in negative nitrogen balance when you restrict calories for fat loss.

What You Should Focus on Instead of Nitrogen Balance

In the book The 4 Disciplines of Execution, the authors make a distinction between what they called lead measures and lag measures

Lag measures are measurements of the results of some other action. For example, losing weight is the result of restricting your calorie intake, and thus would be a lag measure. 

Lead measures are measurements of the actions you can control that affect your lag measures. Using the weight loss analogy again, a lead measure would be how many calories you consume or how many times you go to the gym. 

The best way to think about nitrogen balance is as a lag measure of your muscle-building efforts—it’s the result of other actions, not something to seek out for its own sake.  

So, instead of fretting about whether or not you’re in a positive nitrogen balance, focus instead on the things that actually move the needle: your workout program, your meal plan, your sleep habits, and your supplementation routine. 

If you’re like to learn more about these things, here are the best places to start: 

The 12 Best Science-Based Strength Training Programs for Gaining Muscle and Strength

The Definitive Guide on How to Build a Workout Routine

The Definitive Guide to the “Push Pull Legs” Routine

The Definitive Guide to Effective Meal Planning

This Is the Best TDEE Calculator on the Web (2020)

7 Proven Ways to Sleep Better Than Ever Before

The 3 Best (and Worst) Muscle Building Supplements

The 3 Absolute Best (and Worst) Fat Loss Supplements

The Bottom Line on Nitrogen Balance

Nitrogen balance refers to the relationship between how much nitrogen you’re consuming (mostly in the form of dietary protein) and excreting (primarily through urine), and positive nitrogen balance refers to a state where you’re consuming more nitrogen than you’re excreting.

According to some fitness gurus, maintaining a positive nitrogen balance is the sine qua non of building muscle. Do that, and you can build muscle even if you’re in a calorie deficit, thus achieving body recomposition. 

The truth is that nitrogen balance—positive or negative—isn’t an accurate predictor of your ability to build muscle. 

What’s more, it’s also not something you can directly control, and thus isn’t worth worrying about if you just want to get bigger, leaner, and stronger.

Instead, focus on following a well-designed strength training program, eating enough calories and protein, getting enough sleep, and taking the right supplements, and you’ll build muscle.

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What’s your take on nitrogen balance? Have anything else to share? Let me know in the comments below!


+ Scientific References

Munro, H. N. (1978). Energy and protein intakes as determinants of nitrogen balance. Kidney International, 14(4), 313–316.
Helms, E. R., Aragon, A. A., & Fitschen, P. J. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: Nutrition and supplementation. In Journal of the International Society of Sports Nutrition (Vol. 11, Issue 1, pp. 1–20). BioMed Central Ltd.
Wolfe, R. R., Wolfe, M. H., Nadel, E. R., & Shaw, J. H. F. (1984). Isotopic determination of amino acid-urea interactions in exercise in humans. Journal of Applied Physiology Respiratory Environmental and Exercise Physiology, 56(1), 221–229.
Tipton, K. D. (2008). Protein for adaptations to exercise training. European Journal of Sport Science, 8(2), 107–118.
Walberg, J. L., Leidy, M. K., Sturgill, D. J., Hinkle, D. E., Ritchey, S. J., & Sebolt, D. R. (1988). Macronutrient content of a hypoenergy diet affects nitrogen retention and muscle function in weight lifters. International Journal of Sports Medicine, 9(4), 261–266.
Pikosky, M. A., Smith, T. J., Grediagin, A., Castaneda-Sceppa, C., Byerley, L., Glickman, E. L., & Young, A. J. (2008). Increased protein maintains nitrogen balance during exercise-induced energy deficit. Medicine and Science in Sports and Exercise, 40(3), 505–512.
Janssen, I., Heymsfield, S. B., Wang, Z. M., & Ross, R. (2000). Skeletal muscle mass and distribution in 468 men and women aged 18-88 yr. Journal of Applied Physiology, 89(1), 81–88.
Helms, E. R., Zinn, C., Rowlands, D. S., & Brown, S. R. (2014). A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: A case for higher intakes. In International Journal of Sport Nutrition and Exercise Metabolism (Vol. 24, Issue 2, pp. 127–138). Human Kinetics Publishers Inc.
Mori, H. (2014). Effect of timing of protein and carbohydrate intake after resistance exercise on nitrogen balance in trained and untrained young men. Journal of Physiological Anthropology, 33(1), 24.
Burd, N. A., Tang, J. E., Moore, D. R., & Phillips, S. M. (2009). Exercise training and protein metabolism: Influences of contraction, protein intake, and sex-based differences. In Journal of Applied Physiology (Vol. 106, Issue 5, pp. 1692–1701). J Appl Physiol (1985).
Lemon, P. W. R., Tarnopolsky, M. A., MacDougall, J. D., & Atkinson, S. A. (1992). Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. Journal of Applied Physiology, 73(2), 767–775.
Tessari, P. (2007). Nitrogen Balance and Protein Requirements: Definition and Measurements. In Cachexia and Wasting: A Modern Approach (pp. 73–79). Springer Milan.
Arnold, A., Sajitz-Hermstein, M., & Nikoloski, Z. (2015). Effects of varying nitrogen sources on amino acid synthesis costs in Arabidopsis thaliana under different light and carbon-source conditions. PLoS ONE, 10(2).
Fields, S. (2004). Global Nitrogen: Cycling out of control. In Environmental Health Perspectives (Vol. 112, Issue 10, p. A556). Public Health Services, US Dept of Health and Human Services.

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