Can Sauna Sessions Help with Sustainable Weight Loss?

When I first started exploring sauna and weight loss, I was fascinated by the reference from Susanna Soberg (The Academic Queen of contrast therapy) , that you could lose 500g in just 20 minutes—just by sitting in a sauna. TBF It’s a well-known tactic in combat sports like boxing and MMA for making weight before competitions. But as I dug deeper, I realised this kind of rapid weight drop is mostly water loss, not actual fat reduction.

Water Weight Loss Isn’t Fat Loss

Studies show that during a traditional Finnish sauna session (around 90°C), you can lose around 0.65 kg (1.4 lbs) in a single session—but that’s primarily fluid loss from sweating. As soon as you rehydrate, the scale tips right back up. So, while it might seem like weight loss, it’s not the kind that leads to lasting changes in body composition.

Infrared vs. Traditional Sauna: A Balanced View

Here’s where it gets interesting. A 16-week study at Binghamton University found that participants using infrared saunas three times a week for 45 minutes lost up to 4% of their body fat over the course of the study. 

While this study specifically used infrared saunas—which heat the body through infrared radiation—the core mechanism of calorie burning and metabolic stimulation is likely similar to traditional saunas.

In both types of sauna:

• Your heart rate increases (like light cardio).

• Your body expends energy (burns calories) to maintain core temperature.

• You experience potential metabolic benefits like improved insulin sensitivity and better cardiovascular function.

Calorie Burn in Saunas

Estimates suggest that a 60-minute sauna session can burn between 100 to 600 calories, depending on factors like body size, metabolism, and sauna conditions. A quick google check reveals  (depending on metabolism!!) that this is roughly equivalent to:

• Rowing for 60 minutes

• Brisk walking for 124 minutes

• Swimming for 83 minutes

• Circuit training for 62 minutes

• Running at a 12-minute mile pace for 62 minutes

....and while sauna should never be used as an excuse (I admit i have used it as an excuse!!)  to skip training or won’t replace a gym session, it can complement an active lifestyle. 

Plus, sauna sessions will help with stress reduction, muscle recovery, and even motivation—all of which support weight management in the long run.

Sustainable Fat Loss: 

More Than Just Heat

This journey has taught me that while saunas alone aren’t a magic fat-burning solution, they can be part of a holistic approach to fat loss and overall wellness. Combining regular sauna use with:

• A nutritious, balanced diet

• Consistent exercise

• Healthy sleep and hydration

• Stress management

…can create the conditions for sustainable fat loss, as supported by the Binghamton study and emerging research on sauna use.

Takeaway

Sauna sessions aren’t just about sweating out water weight. With consistent use, they may contribute to real, sustainable reductions in body fat as part of a healthy lifestyle. The key is balance: see sauna as a supportive tool, not a standalone solution.