First things first: You CANNOT only consume water during longer bouts of exercise.
YOU MUST ALSO TAKE IN ELECTROLYTES to avoid HYPONATREMIA — a potentially deadly condition caused when electrolyte imbalances occur and motor functions begin to shut down.
Sorry for the internet yelling… we like you too much to let you die out there. (Read more here.)
Now that we have that out of the way… onward.
There are a lot of people who would love to hear about losing 6 pounds or more of body weight in 2 hours.
They would likely pay hundreds of dollars to find out the “secret.” The “secret” in this scenario is improper hydration during higher-temperature outdoor training — and it is our goal to make sure this DOES NOT happen to you.
As most of you have already figured out: it is HOT outside!
With this heat comes increased sweating. Increased sweating leads to rapid water and sodium loss, which is NOT good for performance or health.
We’ve had athletes drop 6+ pounds in just 2 hours of training. As the mercury rises, so too should your fluid intake.
The Answer: Calculate Your Sweat Rate
Everyone has different hydration needs. Temperature, intensity, and workout duration all play a role. The best way to dial things in is to calculate your personal sweat rate.
Here’s how our athletes do it:
- Step 1: Choose a quality workout (about 60–90 minutes). Weigh yourself without clothes before you start.
- Step 2: Track the total fluid ounces (or mL) consumed and the workout duration.
- Step 3: Weigh yourself again post-workout (no clothes).
- Step 4: Add together: total fluid consumed + body weight lost (1 lb = 16 oz, or 0.45 kg = 473 mL).
- Step 5: Divide that number by the total workout minutes.
- Step 6: Multiply by 60 to get your sweat loss per hour.
Example: You rode 75 minutes, drank 24 oz, and lost 1 lb.
Total = 24 + 16 = 40 oz.
40 ÷ 75 × 60 ≈ 32 oz/hr (~950 mL/hr).
Don’t be surprised if your number feels high! Many trained athletes fall in the 32–60 oz/hr (0.9–1.8 L/hr) range during intense, hot training. We’ve even seen rates as high as 4L/hr — but that’s rare.
Re-test often in different conditions (heat, duration, workout type). More data points = better accuracy and performance.
Note 1: Some weight loss is expected in long sessions. The goal is to avoid the extremes.
Note 2: If you gain weight during a workout, you’re likely over-hydrating or overdoing sodium intake.
Want more info?
👉 Check out our 10 Heat Beatdown Avoidance Tips
👉 Have questions about what you should be drinking? Contact us here.
Test this out and leave a comment: Let us know your sweat rate number! Include the heat index and workout intensity so we can compile better data for everyone.