Ammonia Smell During Exercise on Ketogenic Diet – Q&A

Question: My question relates to the pungent smell of ammonia in my sweat during a hard work out, seems to start about 45 minutes in and gets stronger from then. This started very soon after the diet. I have recently started a high protein slow carb diet,am drinking between 3 and 4 litres of water a day (currently 180lbs with 21% body fat)have plenty of energy and feel alert and well.  From your work I gather this could be the result of ketosis and burning protein and fat for energy?

Two questions please:
1. Is this OK?
2. Is there anyway to eliminate the smell?

Answer: This is a fairly common report on very low-carbohydrate/ketogenic diet (defined, once again, as any diet containing less than 100 grams of carbohydrate per day), a report of a fairly strong ammonia smell in the sweat during exercise.  As I discuss in detail in my first book The Ketogenic Diet this ammonia is produced due to the ultimate breakdown of ATP to ADP to AMP and ammonia.

This appears to occur more readily when muscle glycogen is depleted (as occurs with the combination of of a very low-carbohydrate intake along with training) and may be part of the increased protein requirements that have been known to occur with endurance training (this is discussed in detail in The Protein Book).  I would mention that it appears that this ‘protein breakdown’ is not actually coming from the breakdown of skeletal muscle itself; rather it’s from the breakdown of BCAA (branched-chain amino acids) within the free amino acid pool.

So is this ok?  So long as dietary protein intake is sufficient, I don’t see this as being any real problem.  The effect is slight in terms of the absolute amount of protein being broken down (in terms of grams) and so long as protein intake is sufficient, there shouldn’t be any detrimental effect other than the smell.

And how do you get rid of the smell?  Well, either wear strong deodorant or raise your carbohydrate intake above the ~100 g/day cutoff point so that you’re not in ketosis.  That’s really all I’ve got solution wise since it’s just one of those biochemical processes that is going to occur during long-duration workouts on a ketogenic diet.  All the best!

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3 thoughts on “Ammonia Smell During Exercise on Ketogenic Diet – Q&A

  1. Thank you for covering this. What could cause the smell if the protein intake is not sufficient? Would it be skeletal muscle breaking down?

    My question is because my husband has had this issue. He doesn’t train and I don’t know if he gets adequate protein. He will go out and mow the lawn and the ammonia smell is overpowering. I have thrown shirts out rather than wash them.

    Blood tests show that functions are normal-kidneys, liver, etc.

    I told him to drink more water but then it got cooler out, so less sweating, We tried to narrow it down to when it started and if he changed anything in his diet. The only thing that came up was enteric coated fish oil caps.

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