Why You Shouldn’t Be Smelling Ammonia When You Train
If your workout clothes carry a sharp ammonia scent, it’s your body’s chemical SOS, not a badge of grit. That odor signals that you’re running low on glycogen and starting to burn protein — exactly what your body tries to avoid during performance.
The Problem: Running on Fumes
At Total Endurance, we recently tested an athlete who couldn’t figure out why training felt harder, recovery dragged, and progress stalled. His clue? An intense ammonia smell after longer sessions. He was eating around 2,000–2,500 kcal daily, assuming that matched his needs.
Our Resting Metabolic Rate (RMR) test revealed his baseline energy use was already 2,300 kcal per day, That’s the energy his body needs just to tick over. As he was trying to lose weight he kept control on his daily calorie intake. However, this 2300 kcal his body needs is before any exercise, work, or life activity. He wasn’t in a mild deficit; he was severely under-fuelling. That chronic energy gap explained the exhaustion, poor recovery, and the unmistakable ammonia aroma.
His body burns ~2300 kcal/day at rest, yet he was only consuming 2000-2500 kcal/day. He was barely covering his body’s basic energy needs.
The Science: Why That Smell Appears
When carbohydrate stores dip too low, the body has to find another way to keep producing ATP. It starts breaking down amino acids from muscle tissue, releasing ammonia (NH₃) as a byproduct.
Normally, the liver converts ammonia to urea for excretion, but during glycogen depletion, extra ammonia leaks into sweat and breath - giving off that biting odor.
It’s often triggered by:
Low carb intake or fasting before training
Long or high-intensity workouts
Chronic under-fuelling or energy deficiency
Dehydration making sweat more concentrated
This isn’t “fat burning.” It’s your body cannibalising muscle for energy — an unmistakable red flag.
Rebuilding the Athlete’s Fueling Plan
We rebuilt our athlete’s fueling plan directly from his tested RMR. Instead of guessing, we scaled his daily intake with training demands to restore metabolic balance and protect muscle mass.
RMR and RER testing quantified exactly how much fat and carbohydrate our athlete was burning at rest, highlighting a balanced metabolism when properly fueled
The Data: Using RMR to Fuel Intelligently
We rebuilt our athlete’s fueling plan directly from his tested RMR. Instead of guessing, we scaled his intake with training demand to restore balance and protect muscle:
Within weeks, the results were dramatic:
The ammonia smell vanished.
Recovery and sleep improved.
Training intensity and endurance rebounded.
By matching his intake to his metabolism, he stopped burning protein and started training efficiently again.
Key Takeaway
If your sweat smells like ammonia, don’t ignore it — it means you’re under-fuelled.
RMR testing eliminates guesswork by revealing what your body truly needs at rest and helping you scale intake properly across training phases
At Total Endurance Coaching, our metabolic testing helps you understand:
How many calories you actually burn at rest
How efficiently you use carbs and fats for energy
How to eat to improve recovery, performance, and body composition