Does Sauna Burn Calories

The idea that simply sitting in a sauna can help you burn calories sounds too good to be true — and for the most part, it is. Saunas are praised for relaxation, muscle recovery and cardiovascular benefits, but their role in actual calorie burn is often misunderstood. While it’s true that your body works harder to cool itself in the heat, the real question is: does that effort significantly increase your energy expenditure? Here's the truth behind whether saunas really burn calories and how that fits into your health or weight-loss plan.

Do You Burn Calories in a Sauna?

Yes — you do burn calories in a sauna, but not as many as most fitness myths claim. Sitting in a sauna raises your core body temperature, and your body responds by increasing heart rate and sweating to cool down. These processes use energy, which results in a modest increase in calorie burn.

Estimates suggest that 15 to 30 minutes in a sauna can burn between 30 and 60 calories, depending on your weight, fitness level and how hot the sauna is. That’s similar to what you'd burn during a slow walk — far from a substitute for real exercise, but not entirely insignificant either.

Why Calorie Burn in a Sauna Is Limited

The main reason sauna calorie burn is modest is because you're not moving. Unlike cardio or resistance training, which actively engages your muscles, sitting in a sauna is a passive experience. Your increased heart rate and sweat are the body’s cooling mechanisms, not indicators of high energy expenditure. The sweat loss often leads people to assume fat is being burned, but the reality is that most of what’s lost is water weight, which will return as soon as you rehydrate.

How Saunas Affect Water Weight, Not Fat

One of the most misleading aspects of sauna use is weight loss on the scale. After a long sauna session, it’s common to weigh 1 to 2kg less — but this is almost entirely fluid loss, not fat. Once you drink water and rehydrate, your weight will return to normal. Saunas can be helpful for temporary weight cuts, such as in combat sports, but they are not effective for long-term fat loss.

Nutritional Breakdown: None, Because You’re Not Eating

Because you’re not consuming anything in a sauna, there’s no nutritional profile to assess — no calories, no fat, no carbs. However, hydration and electrolyte loss can become an issue. Prolonged sauna use leads to the loss of sodium, potassium, and other electrolytes, especially if you sweat excessively without replenishing fluids. This can result in fatigue, dizziness, or muscle cramps.

After a sauna session, it’s wise to drink water with electrolytes or consume hydrating foods to restore balance — particularly if you’ve been in for longer than 20 minutes.

Benefits of Sauna Use

While calorie burn in saunas is minimal, the health benefits are broader. Saunas can improve circulation, help with muscle recovery, and promote relaxation, which may aid sleep and reduce stress. Infrared saunas in particular are known for penetrating heat deeper into tissues, which some studies suggest may support muscle recovery and pain relief.

There’s also evidence to suggest that regular sauna use may improve cardiovascular function, especially when combined with exercise. Some researchers have found links between sauna use and reduced risk of heart disease and hypertension, likely due to the cardiovascular effects of heat exposure.

Downsides and Safety Concerns

While generally safe for healthy individuals, saunas come with risks if overused or misused. Extended sessions, especially without proper hydration, can lead to dehydration, heat exhaustion, or even heat stroke. People with cardiovascular issues, low blood pressure, or certain chronic conditions should consult a medical professional before using saunas regularly.

Drinking alcohol before or during a sauna session increases the risk of complications and should be avoided entirely. Pregnant women and people with kidney conditions are also advised to use caution.

Impact on Your Diet and Fitness Goals

In terms of actual calorie management, sauna use should not replace physical activity or dietary control. The calorie burn is too low to make a meaningful dent in your daily energy balance. However, if used as part of a healthy routine — including exercise, sleep, hydration and nutrition — saunas can support recovery, relaxation and temporary appetite suppression, which may indirectly help with diet adherence.

Some people find that sauna use reduces evening cravings or emotional eating, especially when used to unwind or as a post-workout habit. But again, this is a behavioural benefit, not a direct calorie-burning effect.

Where Sauna Use Falls on the GI Index

Saunas have no glycaemic index because they do not involve food. However, by improving blood flow and reducing stress, sauna sessions may help with blood sugar control indirectly. Chronic stress is known to increase cortisol levels, which can negatively affect insulin sensitivity. By supporting stress management, sauna use may offer a secondary benefit for those managing blood glucose levels.

Still, this is not a replacement for proper dietary or medical care in people with diabetes or insulin resistance.

Healthy Alternatives If Calorie Burn Is Your Goal

If your main focus is burning calories, sauna sessions are best viewed as a supplement to — not a substitute for — actual exercise. Activities like brisk walking, cycling, swimming, or resistance training burn significantly more calories and offer the added benefits of cardiovascular and muscular fitness.

That said, using a sauna after exercise can support recovery and relaxation, making it a valuable add-on rather than a stand-alone weight loss strategy.

Calorie Burn Varies by Sauna Type

Not all saunas are equal when it comes to calorie burn. A traditional Finnish sauna typically operates at 70–100°C with low humidity, causing intense sweating and a noticeable increase in heart rate. Infrared saunas, which use light waves to heat the body directly, work at lower temperatures (usually 40–60°C), but they can cause deeper tissue penetration and potentially a longer calorie burn post-session, as your body takes more time to cool down.

The differences in heat source and intensity can lead to slightly different metabolic responses, though neither type rivals the calorie expenditure of real exercise.

The “Afterburn” Effect Is Minimal

Some sauna users believe in an “afterburn effect” — where the body continues to burn calories even after exiting the sauna. While there may be a very mild continuation of increased heart rate and metabolic activity as your body returns to its normal temperature, this effect is minimal. It’s nowhere near the afterburn (EPOC – excess post-exercise oxygen consumption) you’d get from high-intensity exercise or weight training.

In other words, once you're back to a normal state, the extra calorie burn ends quickly.

Sweating Doesn’t Equal Fat Loss

A common myth is that the more you sweat, the more fat you’re burning. In reality, sweating is a cooling mechanism, not a sign of fat oxidation. You could be burning a high number of calories doing circuit training without sweating much, or sweating buckets in a sauna with minimal calorie expenditure. Fat loss comes from a sustained caloric deficit over time, not from temporary sweat loss.

Saunas help shed water weight, not body fat.

Saunas May Reduce Inflammation — Indirectly Supporting Fat Loss

Chronic low-level inflammation is associated with obesity, insulin resistance and metabolic disease. Some studies suggest that regular sauna use may help reduce markers of inflammation in the body, such as C-reactive protein (CRP). While this doesn’t directly burn fat, lower inflammation may improve metabolic health, making fat loss more efficient in the long term when paired with proper nutrition and exercise.

Psychological and Behavioural Benefits

Another underrated benefit of sauna use is its potential to support healthy routines. People who regularly use saunas often report better sleep, lower stress, and improved mood stability. These effects can make it easier to stick to a healthy diet, reduce stress eating, and recover more effectively from workouts.

By reinforcing a positive health identity — that is, associating yourself with healthy behaviours — sauna use may offer long-term psychological reinforcement, even if the calories burned per session are minor.

Saunas Are Not Suitable for Everyone

It’s worth re-emphasising that saunas aren’t ideal for everyone. People with heart conditions, low blood pressure, kidney issues, or certain autoimmune diseases should consult a healthcare provider before using saunas regularly. The heat puts strain on the cardiovascular system, which may be dangerous in at-risk individuals, even if the calorie burn is relatively low.

Pregnant women are generally advised to avoid saunas, particularly in the first trimester, due to potential risk of overheating and its effects on foetal development.

Summary

Sitting in a sauna does burn calories, but the amount is modest — around 30 to 60 calories for a 15–30 minute session, depending on individual factors. Most of the “weight loss” experienced is water weight, not fat, and returns quickly after rehydration. While not useful for burning significant calories, saunas offer health and recovery benefits when used safely and in conjunction with a well-rounded diet and exercise routine. Think of them as a wellness tool, not a weight-loss shortcut.