Do hot tubs burn calories? Short answer, yes, a little. Soaking in hot water raises core temperature and nudges energy use through passive heating. It won’t replace a brisk walk, yet it can give you a modest burn while you unwind, with helpful side benefits like better sleep and lower stress that support healthy weight over time.
In this guide we break down the real numbers, what the research says, how to soak safely, and smart ways to pair your spa with everyday movement so you feel the difference where it counts.
What you’re really asking
You want to know if a soak can pull its weight, helping you unwind and still “count” towards health goals. You’re not alone. Parents are busy, evenings are short, and if the tub can do double duty, great. Here’s the clear read.
The short answer
Yes, hot tubs can burn calories, but they’re not a replacement for moving your body. A soak gives you a gentle lift in energy use via heat, not effort. Think of it as a small bonus while you relax, not the main event.
How many calories does a hot tub burn, roughly?
One of the best quoted figures comes from research led by Loughborough University. In that small study, an hour in very warm water burned about 140 calories, roughly similar to a 30 minute walk, and peak blood sugar after eating was about 10 percent lower than after a matched cycling session.
The sample was small and all men, so treat the number as a guide, not gospel, but it gives the right scale.
Why passive heating nudges calorie burn
Sitting in hot water raises core temperature. Your body works to shed heat, pumping blood to the skin and making heat shock proteins that help cells cope with stress. That response costs energy, hence the extra calories. Evidence links these heat shock proteins with better insulin function, which may help with blood sugar control in some people.
Health upsides beyond calories
There’s more to like. Warm-water sessions can lower post-meal blood sugar in some setups, and the general picture on passive heating points to cardiovascular perks in certain groups. Also, timing a warm bath or shower 1 to 2 hours before bed has been shown to help people fall asleep faster and improve sleep quality, a quiet win for weight management and mood when life with kids is full on.
Where hot tubs can’t compete with exercise
Here’s the straight talk. Exercise does far more than burn calories. It builds fitness, strengthens hearts and muscles, and supports long term weight control. UK guidance recommends adults aim for 150 minutes of moderate activity a week, plus muscle strengthening on at least 2 days. A tub can support recovery or offer a small calorie bonus, but it doesn’t replace a brisk walk, a bike ride, or a pushchair run round the park.
Who should be cautious
If you’re pregnant or have a health condition affected by heat, speak to a clinician before using hot water for long sessions. And just to keep the family safe, babies and under fives should not use hot tubs at all. We cover that in detail here, Can babies go in hot tubs?
Simple tips to use a hot tub well
Keep it practical and safe while you enjoy the benefits.
- Keep the water in the comfortable range for adults, usually 37 to 39°C, and stay well hydrated.
- Aim for short, calm sessions. If you’re chasing sleep benefits, try a warm bath or tub soak 60 to 120 minutes before bed.
- If weight control is the goal, pair regular movement with sensible nutrition, then use the tub for recovery, stress relief, and that modest calorie bump.
- If you monitor glucose, be aware responses vary. Some research protocols have shown different acute effects on post-meal glucose depending on timing and temperature.
FAQ
Is there a magic temperature that burns more calories?
Hotter water drives a stronger heat response, which may nudge calorie burn up, but safety and comfort come first. Most hot tubs sit 37 to 40°C. Start lower, shorten sessions, and listen to your body.
Can I swap a walk for a soak?
No. The study figure of about 140 calories took a full hour in very hot water, and it still fell well short of what exercise delivers for fitness and health. Use both for different benefits.
Does a tub help with sleep, which also affects weight?
Yes, a warm bath or shower 1 to 2 hours before bed can help you fall asleep faster and improve sleep efficiency. Better sleep supports appetite control and recovery.
Do all studies agree on blood sugar effects?
Not exactly. Some protocols show lower post-meal peaks after heat, others report higher glucose in the short term, which is why personal testing and medical advice matter if you manage a condition.
Do hot tubs burn calories? The bottom line
Yes, hot tubs can burn calories through passive heating. A good rule of thumb from lab work is about 140 calories for a full hour in very warm water, roughly the same as a steady 30 minute walk. That said, a tub isn’t a shortcut to fitness, it’s a complement.
The smart play is this, keep moving most days for your heart, muscles, and long term weight control, then use the hot tub for recovery, stress relief, better sleep, and a small calorie nudge. Keep sessions sensible, stay hydrated, and if pregnancy or a medical condition is in the mix, get personalised guidance first.
For families with young children, remember under fives are a no, and older kids need strict supervision and cooler settings. If you want a spa that makes healthy routines easier, our team can point you to models with simple controls, lockable covers, and water care that takes minutes.
Then you can enjoy the real win, feeling better, sleeping better, and making the most of your time at home.
