The chemical make-up of ammonia is NH3. This means that there is one Nitrogen atom bound to three Hydrogen atoms. Ammonia can be a weak acid or a weak base, depending on what type of chemical it is suspended in. Ammonia has a strong, pungent odor that is easily recognizable in cleaning products, cat urine, and, for some people, sweat!
The key to ammonia in urine and sweat is the nitrogen. The only macronutrient in your body that contains nitrogen is amino acids, the building blocks of protein. In fact, many bodybuilders are always seeking a "positive nitrogen balance" meaning that less nitrogen leaves their body than enters their body. Since nitrogen is in every amino acid, and amino acids are the building blocks of muscle, someone in positive nitrogen balance is more than likely gaining muscle mass.
Your body uses amino acids for energy every day. There is no way to avoid this. Your body constantly goes into catabolic (tissue breakdown) and anabolic (tissue building) phases. When you accumulate mass (lean or fat), your anabolic phases exceed your catabolic phases, but you still experience both phases. When your body uses an amino acid for energy, it must convert the amino acid to a useable form of energy.
It does this by stripping the nitrogen atom off of the molecule. The skeleton molecule that is left behind is then further converted into glucose and used as fuel. In order to get rid of the excess nitrogen, your body typically processes the nitrogen in your kidneys and forms urea, CO(NH2)2 - basically, a carbon dioxide molecule bound to nitrogen and hydrogen. Urea is then excreted in the urine. If your kidneys cannot handle the load of nitrogen, then the nitrogen will be excreted as ammonia in your sweat.
One other factor to consider is water intake. The methods used for getting rid of excess ammonia, such as urine and sweat, all require water as a transport mechanism. If you are not getting adequate fluid, then the solution (ammonia + water) will not be diluted. Therefore, water plays a definite role. If you are not drinking enough fluids to have at least one or two clear urinations every day, you should drink more.
Based on this explanation, it is clear that your sweat will smell like ammonia only if an excessive amount of amino acids are being used for energy, or you are not receiving adequate water. This helps us find a solution to the problem.
Many people mistakenly believe that ammonia sweat means that their protein intake is not high enough. The body will only utilize protein for energy when it does not have a sufficient supply of fats and carbohydrates. Muscles can use glucose and fat for energy, but your brain requires glucose. Since there is no direct metabolic pathway from fat to glucose, your body will use amino acids instead. If your protein intake is high, there is a chance that the amino acids that supply energy will come from ingested food and not your hard-earned muscle tissue - but why take that chance?
Let's look at an oil lamp. If you fill that lamp with Citronella oil, it will have a distinct odor when you light it. To eliminate that odor, do you add more Citronella? No! That's just fanning the flames. You'd use a different type of oil instead. The same goes for the ammonia smell - this is just the smell of amino acids being "burned" in your body. You don't solve that by adding more amino acids. Instead, you need to supply the fuel that your body prefers - the fuel that can be easily broken down to glucose in order to supply energy to your muscles and your brain - carbohydrates!
The key to avoiding that ammonia smell is to ingest sufficient carbohydrates. If you eat an ample amount of carbohydrate with every meal, then you should have plenty to fuel your exercise activity. Even people who work out on an empty stomach should have some glucose in their bloodstream upon rising - unless they subscribe to the myth that cutting out carbohydrates before bed helps you lose fat. If you find that the ammonia smell persists (even when you consume carbohydrate with every meal), try having a low glycemic carbohydrate before you workout.
A little oatmeal, a small apple, or even a piece of sprouted grain bread can provide the fuel that your body needs. Remember, your body requires fuel to burn fat! So don't think that providing some carbs before cardio is going to eliminate the fat burning process. In fact, most of my clients who consume a light meal before working out report that their energy levels go through the roof, and they have an incredible workout. If adding 80 calories in the form of a slice of sprouted grain bread kicks your energy levels into high gear and helps you burn 100 more calories during exercise (while sparing your muscles from being used as fuel), there is no reason to worry about dropping fat!
Your body can only process a certain amount of food at each meal. Therefore, it may not be possible to avoid that ammonia smell during prolonged activities. The smell is common, for example, amongst marathon runners, who are engaging in continuous cardiovascular exercise for hours at a time. In that situation, it is advisable to consume "sports drinks" or other sources of energy during the activity to fuel your body (and especially your brain) and prevent your amino acids from being burned for energy.
The next time you smell ammonia, don't worry. It doesn't mean that your muscle tissue being broken down, and it doesn't mean that you're doomed to stink for the rest of eternity. Consume a nutritious meal immediately after exercising - a balance of lean protein and whole, unprocessed carbohydrates - and then increase your carbohydrate intake throughout the day, or add a small "snack" prior to your next workout. An apple a day can help keep the ammonia smell away!