How much are you sweating?

Depending on who you talk to, sweat can be a bit of a taboo! Most of us can relate; there’s something particularly embarrassing about rushing to get to a social situation; you come in, looking great, feeling great — then suddenly, realise you rushed just a little too much. Whilst everyone else looks immaculate and composed, you feel yourself starting to sweat.

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But, sweating certainly isn’t unhealthy; on the contrary, it’s absolutely essential, particulary in warmer climates or with increased activity. You might have heard people say “fitter people sweat more” — but is it really true?

Sweating the Basics: Understanding Your Sweat Rate

Before we being, let’s understand your Sweat Rate. What exactly is a sweat rate? Think of it as the speedometer for your body’s water loss during a workout, typically measured in litres per hour. Scientists get really into the details with methods like hygrometry and gravimetry to measure this. Hygrometry involves using a device called a ventilated sweat capsule to monitor air temperature and humidity changes, while gravimetry collects sweat right off your skin. These methods are super accurate, but not exactly practical for everyday athletes (ahem — and not quite athletes like us), training outside the lab.

The simplest and most practical way to figure out your sweat rate during your regular workouts? Just check your weight changes before and after your exercise routine, making sure you account for any drinks you had or trips to the bathroom.

How to Figure Out Your Sweat Rate Easily

Curious about how much water you’re losing during your workouts? Here’s a straightforward way to find out, inspired by experts.

Gear Up: You’ll need a good bathroom scale and a towel. A small kitchen scale will come in handy to weigh your drink bottles.
Prep: Use the bathroom first, then weigh yourself nude to avoid errors from wet clothing.
Weigh Your Drink: Record the weight of your water bottle(s) before you start your workout.
Work Out: Keep an eye on the clock to know how long you’re exercising.
Post-Workout Weigh-In: After your workout, weigh your water bottles again and dry off any sweat before weighing yourself nude once more.
Calculate the Loss: Subtract your post-workout weight from your pre-workout weight to find the weight you’ve lost.
Account for Intake: Also, add back the weight of any water you drank during your workout.

Finally, to get your sweat rate, divide the total weight change by the duration of your workout in hours:

Sweat Rate (L/h) = Weight Lost + Water Consumed / Exercise Duration

A few facts about sweating…

As you exercise harder, you sweat more. This might sound obvious — but it’s a surprisingly direct relationship. Sweat rate increases linearly with exercise intensity, at least for a while!
You can learn to sweat more. It’s called “acclimatisation”, and it has a huge impact. If an average sweat rate is 1.5 litres per hour, proper acclimatisation can increase that to 2–3 litres, or up to 100%!
Sweat is more than just water. While we often think of sweat simply as water, it actually contains a variety of electrolytes, most notably sodium. This is why after intense exercise, you might notice white marks on your clothes — it’s the salt left behind from evaporated sweat. Maintaining the balance of these electrolytes is crucial for your body’s hydration and overall function.
Not everyone sweats the same way. There’s considerable variation in how much and how quickly people sweat, and it’s influenced by genetic factors, fitness levels, and environmental conditions. For example, people who are more fit tend to start sweating sooner during exercise as their bodies are more efficient at regulating heat.
Sweat can tell a health story. Monitoring your sweat can be a window into your health. Changes in the amount or type of sweat can indicate hydration levels, nutritional imbalances, or even underlying health issues. Some modern fitness technologies and wearables are designed to analyze sweat to help provide insights into your physical state and needs.