QUESTION: what percentage of calories from protein, carbs, and fat do I need in my diet to remain in a caloric deficit and in a state of positive nitrogen balance?

See: https://www.youtube.com/watch?v=Bz3AG-oCXTE&t=394s

I'm just starting to exercise regularly (mostly focused on HIIT) and diet properly. Soon, I'd like to focus on also building muscle. As I still have a lot of fat to shed (I'm 5'11", 213 lbs / 96.6 kgs), I believe I need to remain in a caloric deficit. And in order to help my muscle building efforts, it seems that I need to be in a state of positive nitrogen balance.

Per http://www.bodybuilding.com/fun/drobson75.htm, I think I need at least 1.7 grams (maybe even up to 3.5 grams) of protein per kilogram of body weight per day. On the low end, that means I need at least 96.6 kgs x 1.7 grams/kg = 164 grams of protein per day. In calories, that's:

   164 grams of protein
 x   4 calories per gram of protein
 = 656 calories from protein

I have a budget of 1,780 calories per day to remain in a caloric deficit and lose up to 2 lbs per week. So about 37% of my calories should come from protein. I have 63% to split between carbohydrates and fat -- and I'm not sure how to do it.

UPDATE: http://www.bodybuilding.com/fun/mhptrans6.htm seems to suggest 45% carbohydrates, 35% proteins, 20% fats. Is this right? Would I achieve positive nitrogen balance with this ratio?

2 Answers 2


Nitrogen Balance is just how you measure overall nitrogen accumulation, which is a pretty reliable indicator of muscle growth; positive NB is more amino acids staying on your body than pissed out (muscle growth) and negative NB is the opposite.

According to the International Society of Sports Nutrition, a protein intakes of 1.4-2.0 g/kg of bodyweight (0.6-0.9g/lb of bodyweight) for physically active individuals is not only safe, but may improve the training adaptations to exercise training. [1]. The American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine also support high protein intake for active individuals [2] in the range of 1.2-1.7 g/kg of bodyweight (0.5-0.8 g/lb of bodyweight).

The reasons for the above tend to be increased leucine oxidation (a marker for amino acids being used for fuel, by being turned into glucose) that requires a higher intake of amino acids to negate and preserve nitrogen balance. [3][1] Additionally, increasing protein intake above the previously defined RDA 'daily allowance' will increase protein synthesis and, at levels higher than double this total, decrease protein breakdown. [4] Increased muscular hypertrophy is seen as beneficial to sports performance.

  • [1]: Campbell B, et al International Society of Sports Nutrition position stand: protein and exercise . J Int Soc Sports Nutr. (2007)
  • [2]: Rodriguez NR, DiMarco NM, Langley S; American Dietetic Association; Dietetians of Canada; American College of Sports Medicine Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance . J Am Diet Assoc. (2009)
  • [3]: Wilson J, Wilson GJ Contemporary issues in protein requirements and consumption for resistance trained athletes . J Int Soc Sports Nutr. (2006)
  • [4]: Jeevanandam M, et al Influence of increasing dietary intake on whole body protein kinetics in normal man . Clin Nutr. (1986)

Source: Examine.com


You are massively over-thinking your food. As a beginner to weightlifting you will lose fat and gain muscle during a calorie deficit. However, as you progress past "beginner" and linear progressions no longer work for you, you should re-evaluate your diet and consider eating at a maintenance calories (if you want to maintain) or at a 'bulk' (surplus calories).

Option's are divided as to the "optimal" macro-nutritional breakdown and current advice does not go into finer detail because only you know your body and how it is feeling and so only you can plan your dietary needs accordingly.

For example, I went hard last week at crossfit and so I ate more this weekend to give me some fuel and protein to recover.

In terms of splitting up fat and carbs, just split however you want. More carbs will give you more energy but less overall food in your mouth.

  • "As a beginner to weightlifting you will lose fat and gain muscle during a calorie deficit." - this is a pretty simplistic comment. Gaining, or, maintaining muscle mass during a caloric deficit is much harder than your comment makes it appear.
    – rrirower
    Dec 6, 2016 at 16:17
  • I didn't say it was easy, just that it is possible and common.
    – John
    Dec 7, 2016 at 7:46

Positive nitrogen balance is an indicator of you being in an anabolic state, meaning you are synthesising protein.This is only an indication of what the protein in your body is being utilised for.

If you are taking on too little carbohydrate, your body will utilise both protein and fat for energy; resulting in negative nitrogen balance. You are then likely to be in a state of catabolism, meaning you could be losing lean mass.

For strength training athletes, 2g protein per kg of body mass is a good starting point for protein synthesis. Any intake above 2.4kg body mass is considered to be of little benefit for gains in muscle mass.

Both carbohydrate and protein will add 4kcal per gram to your diet, fat will add 9kcal per gram.

Good fats are essential in your diet but are costly in terms of energy, aim to keep total fat below 20% of total energy allowance; aim for monounsaturated and polyunsaturated fat sources, avoid saturated and trans-fats.

Focus on the intake of complex carbohydrates i.e brown rice as opposed to simple carbohydrate i.e. white bread. Read about glycaemic index/glycaemic load and how it relates to exercise. Timings for the intake of different types of carbohydrate will make a huge difference to outcomes. If you time carbohydrate intake effectively, you can worry less about anabolic windows post workout.

As a rule of thumb 3500kcal is equal to one pound fat. Aim to lose between 1 and 2lbs per week when stripping, any more and you will likely sacrifice lean mass. Be patient, it pays to be conservative.

REMEMBER: protein is expensive fuel, train smart. Focus on building a good feedback loop: record what you eat, and your training outcomes. Tweak ratios for what works for you, there are no hard and fast rules and good science will lead you where you want to go. The above are good starting points.

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