Okay… this could easily get dangerously sciencey… But I’ll try to keep it simple…
Ammonia is NH3. The main source of NH3 in our bodies in Amino Acids. Amino Acids are the building blocks of protein. If you don’t fuel yourself properly, your body will break down Amino Acids to use for fuel. When you break down Amino Acids, you can get that ammonia smell.
This can be a sign that you are not getting enough fats and carbohydrates in your diet. Consider this general information (that any dietitian will advise you)
- 25-30% of your daily calories should come from fat
- 45-50% of your daily calories should come from carbs
How low do those numbers need to be in order for your body to start breaking down Amino Acids? I cannot say.
Another possibility is that your water intake is too low. If the ammonia in your body fluids is not diluted enough, it will become apparent in your sweat and your urine. Aim for at least 1 or 2 clear urinations every day.
One other time it is common is in ultra runners. In that case it can only be avoided by careful and proper fueling during the runs. Your body should not need to break down Amino Acids for a weight lifting session (no matter how intense) or an 8k run.