Does Sauna Help with Weight Loss?

Partly: a sauna can lower body weight temporarily when sweating causes water loss, but it has not been shown to produce lasting fat loss.

Research on rapid weight loss in athletes describes sauna as a way to reduce weight before a weigh-in, not as a proven way to lose body fat. If you choose to use a sauna, avoid trying to sweat off weight and take steps to prevent overheating and dehydration. For a broader look at hydration and weight management, see the best drinks for weight loss.

Can a sauna help you lose weight?

A sauna can make the scale show a lower number immediately after a session. That change is mainly water lost through sweat, so your weight can rise again as you drink and rehydrate.

That is different from losing body fat over time. Sauna use has not been established as a reliable method for doing that, and deliberately staying dehydrated to keep the scale down is unsafe.

For lasting weight management, focus instead on an eating pattern and physical activity you can maintain. A sauna can be a relaxation choice if it is safe for you, but it is not necessary for weight loss.

How does a sauna affect body weight?

Heat prompts your body to sweat as it tries to cool itself. Because sweat contains water, losing it reduces your body weight until the fluid is replaced. How much the scale changes varies with factors such as the heat, your time in the sauna and your individual sweating response.

Your heart rate can also rise in the heat, but a faster heartbeat does not show that you are losing meaningful amounts of body fat. An immediate change on the scale cannot tell you whether any fat has been lost.

Sweating also removes only trace amounts of waste. The liver and kidneys do most of the body's detoxification, while the lungs and gut help eliminate waste; drinking enough supports normal hydration and organ function.

What does the research say about sauna and weight loss?

The evidence directly supporting sauna for lasting fat loss is limited. A review of rapid weight loss in combat sports describes sauna use among several methods athletes use to make a weight class. It also reports that rapid weight-loss practices can harm health and physical and cognitive performance.

A survey of 637 combat-sport competitors found that athletes reported using a range of weight-making methods, including sauna. This was a questionnaire about their practices, not a controlled test of whether sauna reduces body fat.

These findings help explain why sauna is used for a short-term scale change. They do not establish that sauna causes sustained fat loss, or that rapid weight cutting is safe for recreational users.

How can you use a sauna more safely?

If you enjoy a sauna and have no reason to avoid it, use it for comfort rather than as a weight-loss tool:

Start with a short visit. Leave if the heat feels uncomfortable; do not try to stay longer just to sweat more.
Drink water before and after as needed. Replace fluids rather than trying to preserve a lower post-sauna weight. If you have been told to limit fluids, follow your clinician's advice.
Avoid alcohol and weight-cutting tactics. Do not combine sauna with fluid restriction, extra insulating clothing, diuretics or other attempts to force rapid weight loss.
Leave promptly if you feel unwell. Dizziness, weakness, nausea or a headache are reasons to stop, move somewhere cooler and rest.
Cool down gradually. Give yourself time to recover before returning to activity, especially if you were already hot after exercise.

Do not force large amounts of water at once. If you weigh yourself, avoid treating the lower number immediately after a sauna as a measure of fat loss.

Who should be careful with sauna use?

Avoid a sauna when you are already dehydrated, ill or feverish. Older adults and people who are sensitive to heat may need extra caution. Children should use a sauna only with appropriate adult supervision and advice from their pediatrician.

Talk with a clinician before using a sauna if you are pregnant or have heart disease, low blood pressure, kidney disease or another condition that affects your ability to tolerate heat or manage fluids. Also ask if you take diuretics, blood pressure medicines or other medicines that may affect hydration or heat tolerance. Do not change or stop prescribed medication to use a sauna.

Seek prompt medical care if dizziness, vomiting or other symptoms persist after you leave the heat, or if you cannot drink. Call emergency services for confusion, fainting, a seizure or suspected heat stroke. Move the person to a cooler place and cool their skin while help is coming; do not give fluids to someone who is unconscious or unable to swallow safely.