Why is it that some people smell like cleaning liquid after a heavy workout? That's because their bodies are processing protein.
When, say, a weightlifter eats a protein-rich diet and exercises afterward, that person's body may turn the proteins into energy. How? By ditching the nitrogen and transforming the remaining molecule into glucose, which the body uses for fuel. The nitrogen, in turn, may then combine to form ammonia, which we can expel as urea through urine. We can also sweat it out [source: Likness].
If your sweat stinks of ammonia, you may want to try to up your carb intake and, of course, see your doctor.