Everyone wants to look and feel their best. Lately, you’ve probably seen claims like:
“Spending 15 minutes in a hot tub is the same as a 10-minute walk,” or “Soak before bed and burn calories while you relax.”
These tempting statements naturally catch the attention of anyone hoping to shed a few pounds—especially those who aren’t fans of traditional workouts. After all, who wouldn’t love the idea of kicking back and slimming down at the same time?
But let’s be real—is it really that easy? Can soaking in a hot tub actually help you burn fat and lose weight?
In this article, Giving Tree Home takes a clear, science-based look at the truth behind “hot tub calorie burning” and separates fact from fiction when it comes to losing weight while you soak.
Myth or Reality?
Yes, hot tubs can help your body burn a small number of calories—so the claim isn’t completely off base.
A 2017 study published in the journal Temperature found that soaking in a hot bath burns about 60 calories per hour—slightly more than what you’d burn just sitting still.
But if you’re hoping to shed pounds simply by lounging in a tub, you might be in for a reality check.
To lose one pound of fat, you need to burn roughly 3,500 calories. At 60 calories per hour, that means soaking for an hour every single day for about two months—just to drop a single pound.
Even if you stuck to that routine for a full year, you’d likely only lose around five pounds—at best.
And there’s another catch: daily, prolonged hot tub use isn’t recommended. Spending too much time in hot water can strain your cardiovascular system, especially if you have high blood pressure or heart issues.
So while hot tubs do slightly boost your body’s energy expenditure, “burning calories” isn’t the same as “burning fat.”
In short, hot tubs are excellent for relaxation and overall wellness—but they’re not a reliable weight-loss tool.
The Science Behind Hot Tub Calorie Burning
The reason you burn a few calories in a hot tub comes down to thermoregulation—your body’s way of keeping its core temperature steady (around 36.5–37.2°C or 97.7–99°F).
When you soak in hot water (about 38–40°C / 100–104°F), that balance is temporarily disrupted, and your body kicks in a series of cooling mechanisms that use extra energy.
The Balance Between Heat Production and Heat Dissipation
Once you settle into the hot tub, heat transfers through your skin, causing your core temperature to rise roughly 0.5–1°C within the first 15 minutes.
To prevent overheating, your hypothalamus triggers two main responses:
- Vasodilation
The tiny blood vessels under your skin expand, letting more blood flow to the surface so heat can escape through radiation and convection.
This makes your heart beat a bit faster—typically 10–20 extra beats per minute—which slightly boosts your energy expenditure.
- Sweating response
If the water temperature exceeds 39°C (102°F) or you soak for longer than 20 minutes, your body starts to sweat.
Even underwater, your sweat glands are active, burning energy. Plus, restoring fluid and electrolyte balance briefly increases your metabolism.
According to the American College of Sports Medicine (ACSM), every 1°C rise in core body temperature can raise your basal metabolic rate (BMR) by 10–15%.
Indirect Long-Term Benefits
Hot tubs can also support your metabolism indirectly through relaxation and recovery:
- Muscle relaxation
Sitting or standing in poor posture can create low-level, continuous muscle tension that quietly uses energy.
Soaking in hot water relaxes muscles, reduces unnecessary energy expenditure, and helps your metabolism work more efficiently.
- Improved sleep quality
Spending 15–20 minutes in a hot tub before bed helps your body temperature gradually drop afterward, triggering melatonin release and better sleep.
Quality sleep supports insulin sensitivity and balances key metabolic hormones like leptin and ghrelin, which can reduce overeating and help prevent metabolic issues.
That said, these are indirect metabolic benefits—not instant fat-burning effects.
The Real Calorie-Burning Effect of Hot Tubs
So, how many calories can you actually burn while soaking in a hot tub?
Here’s a rough comparison for a 60 kg (132 lb) adult:
| Activity | Duration | Calories Burned (approx.) | Description |
|---|---|---|---|
| Resting (sitting) | 15 min | 15–20 kcal | Minimal energy use, just basic metabolism |
| Soaking in a hot tub (38–40°C / 100–104°F) | 15 min | 18–25 kcal | Slight metabolic boost, similar to standing or light movement |
| Slow walking (4 km/h / 2.5 mph) | 15 min | 30–40 kcal | Light activity, steady breathing |
| Brisk walking (6 km/h / 3.7 mph) | 15 min | 55–65 kcal | Moderate activity, light sweat |
| Jogging (8 km/h / 5 mph) | 15 min | 130–150 kcal | Vigorous activity, heavy breathing and sweating |
As you can see, 15 minutes in a hot tub burns only a little more than sitting still—and far less than light or moderate exercise.
Calorie burn also depends on individual and environmental factors:
- Body weight
Heavier individuals expend more energy regulating their body temperature, so they burn slightly more calories.
- Water temperature
The hotter the water, the faster your body warms up, and the more energy it uses to cool down. Temperatures above 40°C (104°F), however, can strain your cardiovascular system and increase the risk of dehydration.
- Soaking time
Your metabolism ramps up in the first 10–15 minutes, then levels off as your body adjusts to the heat. Staying longer doesn’t significantly increase calorie burn.
Bottom line: hot tubs do burn calories, but the effect is modest, highly variable, and nowhere near a replacement for traditional fat-burning exercise.
The True Value of a Hot Tub: Supporting Wellness, Not Burning Calories
While the calorie-burning effect of a hot tub is limited, its health and relaxation benefits are far more meaningful—and arguably more valuable than any so-called “fat-burning” function.
Relieving Post-Workout Fatigue
For those who exercise regularly, soaking in a hot tub can be an excellent recovery tool:
- Speeds up lactic acid removal
After a workout, your muscles build up lactic acid, which causes soreness. The heat from a hot tub boosts blood circulation, delivering more oxygen and nutrients to the muscles. This helps break down lactic acid faster and reduces post-exercise discomfort.
- Relaxes muscle tension
High-intensity training often leaves muscle fibers tight. Warm water helps relax both muscles and fascia, easing stiffness and helping your body recover faster—so you can perform better in your next session.
Improving Blood Circulation
Long hours of sitting can slow blood flow, leading to leg swelling and reduced metabolic efficiency.
Soaking in a hot tub promotes vasodilation, which improves circulation throughout the body. This is especially helpful for returning blood from the lower limbs and reducing swelling.
Better circulation also means more oxygen and nutrients reach vital organs, supporting normal metabolic functions and helping prevent issues like blood sugar spikes or fat accumulation caused by poor circulation.
Reducing Stress and Anxiety
Stress triggers the release of cortisol—the “stress hormone.” High cortisol levels can increase appetite, especially for sugary or fatty foods, often leading to overeating.
Hot tubs help calm the nervous system and lower cortisol levels, easing stress and anxiety. While this doesn’t directly burn calories, it supports energy balance and healthy weight management indirectly by reducing emotional eating.
Regular Bathtubs as an Alternative to Hot Tubs
As we’ve discussed, the calorie-burning effect of a hot tub comes from the slight metabolic boost caused by heat exposure.
In other words, as long as you can create a warm, heat-retaining environment, a regular bathtub can provide similar benefits. So even if you don’t have a hot tub at home, you can still enjoy relaxation and mild metabolic stimulation through other types of baths.
Standard Bathtub — A Practical and Economical Option
The appeal of a hot tub often comes from its massage jets, precise temperature control, and social experience.
However, these features also come with higher costs, more space requirements, and more complicated maintenance.
By contrast, a freestanding bathtub is a much more budget-friendly and user-friendly choice—perfect for anyone who simply wants a comfortable soak.
At Giving Tree Home, we recommend acrylic bathtubs.
Compared with solid surface, ceramic, or cast-iron tubs, acrylic models retain heat better and offer a more comfortable soaking experience thanks to their hollow structure and thermal properties.
According to our internal testing, a Giving Tree Home acrylic bathtub filled with 40°C (104°F) water loses only about 2.5°C (4.5°F) over 20 minutes—enough to provide a warm, restorative soak every day.
Japanese Soaking Tubs — A “Mini Sauna” Experience
For those who want longer soaks, concentrated heat, and a steam-like experience, a Japanese soaking tub is an excellent alternative.
These tubs are typically deeper and more compact, sometimes featuring built-in seats and optional covers to trap steam and heat, creating a mini sauna-like environment.
Unlike standard hot tubs, Japanese soaking tubs focus heat more efficiently. Even without a temperature-control system, the enclosed design retains warmth, providing a stronger sense of immersion and promoting gentle sweating.
Modern Japanese soaking tubs have evolved well beyond traditional wooden styles (also called an Ofuro). They’re now available in acrylic, stone, and stainless-steel options, suitable for both bathing and soaking, and adaptable to a variety of bathroom layouts.
Ending
So, can soaking in a hot tub really burn calories?
The short answer: yes—but the effect is minimal and can’t replace regular exercise or a balanced diet.
Instead of hoping to “slim down while lying still,” it’s better to focus on what a hot tub truly offers:
It’s a wellness companion, not a weight-loss shortcut—a tool for relaxation, recovery, and improved circulation that supports your fitness and diet efforts rather than replacing them.
There are no real shortcuts when it comes to lasting health.
The best way to enjoy a hot tub is to use it as part of a balanced lifestyle:
- After workouts: soak to help your muscles recover
- After long periods of sitting: improve circulation and reduce stiffness
- During stressful times: unwind and calm your mind
By using your hot tub this way, you not only enjoy comfort but also nurture a healthier, more balanced body and mind—which is, ultimately, the most valuable benefit it can offer.
