Ice baths and winter swimming have taken on almost mythical status in recent years. People talk about burning fat, “speeding up metabolism,” and even miracles when it comes to body weight. The reality is much more nuanced.
So how does the cold actually burn calories, and what should you do if jumping into an ice hole feels more like self-torture than a sensible tool for promoting health?
How do ice baths and winter swimming burn calories?
Let’s start with the most important point: cold burns energy, but not in the way most people imagine.
Immediate Energy Expenditure
When you’re in cold water (0–4 °C), your body tries to maintain its core temperature at all costs.
5 minutes in an ice bath burns approximately 40–60 kcal
After getting out of the water, it takes another 20–60 kcal to warm the body back up
In total, this amounts to ~70–110 kcal per session. That’s not exactly a small number, but it’s not revolutionary either. Furthermore, the actual results depend on quite a few factors
The effect of brown adipose tissue
Humans have brown adipose tissue, whose function is not to store energy but to burn it to produce heat. Regular exposure to cold:
activates existing brown fat
improves cold tolerance
increases energy expenditure only while in the cold
The role of the nervous system
Cold activates the sympathetic nervous system:
norepinephrine levels rise
one’s sense of alertness increases
people often move more throughout the day (even without realizing it)
This is one of the additional reasons why cold water treatments can lead to faster weight loss—not because of calories, but because of behavioral changes.
Why does weight drop quickly at first?
Many people experience noticeable weight loss during the first 1–2 weeks after starting winter swimming or ice baths. This is mainly due to:
a reduction in fluid and inflammatory swelling
the release of glycogen (and the water bound to it)
a reduced appetite
This is real weight loss, as shown by the actual numbers on the scale, but it isn’t entirely fat. Regardless, you’ll start to feel lighter and more comfortable fairly quickly. Unfortunately, weight loss at this same pace does not continue in the following weeks.
What, unfortunately, don’t ice baths and winter swimming do? This is where myths collide with reality.
It’s not a miracle fat-burning remedy
A 100-kcal deficit per day does not, on its own, result in significant fat loss.
Fat burning still requires:
an energy deficit
exercise
consistency
It is not a substitute for exercise
Cold shower:
does not build muscle
does not improve endurance
does not increase maximum oxygen consumption
It can support your workout, but it won’t do the work for you.
Doesn’t work indefinitely
The body adapts very well to the cold.
The more accustomed you are to it, the:
less you shiver
more effectively retain heat
the lower your additional energy expenditure
This is an evolutionary survival mechanism; your body gets used to the stress that the cold puts on it.
It’s by no means suitable for everyone
Heart problems, high blood pressure, or excessive stress can make the cold more harmful than beneficial.
If an ice bath seems too extreme—reasonable alternatives
Good news: you can achieve most of the benefits with much gentler methods.
Cold shower
30–90 seconds
Simple and accessible
Stimulates the nervous system without the shock
Contrast shower or sauna + cool water
Supports blood circulation and recovery
Less stress, more enjoyment
More sustainable for many people than an ice bath
Exercise in the cool air
walking in cool weather
lighter clothing
natural heat production through muscles
This is often more effective in terms of calorie burn than passively sitting in the cold.
Managing Stress and Sleep
Many of the “miraculous” effects of cold actually stem from improved nervous system balance, lower cortisol levels, and more consistent appetite. You can often achieve the same results by reducing your stress levels and getting regular, sufficient sleep.
A boring but effective classic is strength training combined with daily exercise, which boosts your long-term metabolism, leads to lasting fat loss, and doesn’t require an ice hole at all.
Summary
Ice baths and winter swimming:
burn calories, but only moderately
indirectly affect body weight, primarily through behavior and the nervous system
are not a shortcut to fat burning
If you enjoy them—great, use them as a tool. If not—don’t worry. The same health and weight benefits can be achieved through much less extreme methods. After all, your body doesn’t ask you how cold or unpleasant it was for you, but what you actually did for your health.
