Some say that cold showers and other forms of cold exposure can help you lose weight. The idea is that stepping under an icy shower will raise your metabolic rate, increasing the amount of fat you burn throughout the day.
I’ve even seen claims that a cold shower can burn an extra 500 calories per day, which is more than a lot of people burn during a typical gym workout.
In truth, while a cold shower does have its benefits, weight loss isn’t one of them.
Research shows that cold exposure increases the metabolic rate by only 1-2 calories per minute. You’d need to spend hours in the shower for it to have any kind of meaningful impact on weight loss.
How Brown Fat Affects Your Metabolic Rate
Making yourself cold by showering in ice-cold water or sliding into an ice bath is supposed to activate brown fat, which in turn generates heat, raises your metabolism and burns off regular fat.
The idea is that you take a cold shower for at least 30 seconds, letting the icy water run over your shoulders, neck and back. Research shows that this is the area where a lot of brown fat cells are found .
The reason it’s brown is because it’s so tightly packed with mitochondria, which is where fat gets burned off.
The primary function of brown fat is to generate heat. In fact, brown fat cells are so metabolically active that just two ounces of the stuff can burn around 500 calories per day, which is a lot more than regular adipose tissue.
Brown fat is normally inactive, just as long as you’re in your thermal comfort zone, which is part of the reason that it’s rarely detected and why brown fat was traditionally thought to be irrelevant in adults.
However, more recent evidence suggests that its expression in adults is far more common than previously thought, with a higher likelihood of detection in women and leaner individuals .
Cold Showers for Weight Loss?
Many of the articles I came across claiming that cold showers help with weight loss cited a 2008 study as solid evidence that taking cold showers can help with weight loss .
When I looked at the study for myself, I was expecting to find two groups of people, one who had taken a cold shower every day for a few months, and another group that had taken a hot shower. And the ones taking cold showers had lost the most weight.
The reality, however, was rather different.
Firstly, subjects in the study spent an entire day in a respiration chamber, which is a small room that allows scientists to measure energy expenditure and metabolism.
There’s a big difference between spending 24 hours in a cold room and stepping under a chilly shower for a few minutes.
On average, mild cold exposure (61 degrees F or 16 degrees C) did increase the number of calories burned. However, there were large individual differences from person to person.
In one of the subjects, there was an increase in daily energy expenditure of around 400 calories per day. In another, calorie expenditure actually dipped by 50 calories.
The average increase across all subjects was only 76 calories. This represents an increase in 24-hour energy expenditure of 2.8%.
In other words, not only is the effect a relatively small one, it seems highly variable from person to person.
You might think that the increase in energy expenditure was caused by the men moving around more to keep themselves warm. But this wasn’t the case. In fact, mild cold exposure led to a significant drop in physical activity.
FREE: The Flat Belly Cheat Sheet. This is a quick guide to losing fat, which you can read online or keep as a PDF, that shows you exactly how to lose your gut and get back in shape. To get a FREE copy sent to you, please click or tap here to enter your email address.
Although the researchers speculate that “regular cold exposure might be beneficial in body weight regulation,” they don’t give any recommendations about how long this cold exposure should last, or how cold you actually need to get.
A follow-up study on the subject of cold exposure and fat metabolism shows that brown fat actually uses regular fat from the rest of the body to fuel itself.
This time, subjects were kept cold, but not to the point of shivering, which itself will burn calories .
Over a 3-hour period, their metabolic rates increased by roughly 80%, going from an average of 1.8 to 3.2 calories per minute.
In fact, the men burned an average of 250 additional calories. This was all from a few ounces of brown fat, which kept the men warm.
There was also a large variation in the amount of brown fat each subject stored, ranging from 31 to 329 milliliters. The more BAT a man had, the colder he could get before he began shivering.
Does this research offer any support for the idea that reducing the water temperature in your shower will help with weight loss?
Not really. To keep them cold, subjects in the study wore a liquid-conditioned tube suit, which had cold water poured into it.
There’s a big difference between having the whole of your body cooled for several hours and standing under a cold shower for 30 seconds.
And even then the rise in metabolism was a relatively small one, averaging 1.4 additional calories burned for each minute of cold exposure.
There’s also some debate about the extent to which BAT is present in obese and overweight individuals.
In fact, some studies show lower BAT activity in people who are overweight or obese. The figure below, taken from this New England Journal of Medicine study, shows how BAT activity declines as body fat percentage increases.
Overall, the number of calories burned tends to be blunted in obese versus lean subjects exposed to the same cold temperatures .
It’s possible that lean adults may require increased metabolism in brown fat for “non-shivering” thermogenesis to maintain body temperature when it gets cold.
This isn’t so much of an issue for someone who is overweight or obese. Their fat stores act as a layer of insulation to keep them warm.
Cold Exposure and Fat Loss
The research I just mentioned looked at the effect of short-term cold exposure on the metabolism.
And while this type of research is interesting, a short-term rise in metabolic rate doesn’t always add up to a greater rate of fat loss over a period of weeks and months.
Will making yourself cold help you lose fat faster?
In one study, scientists found that sleeping in a cold room (66 degrees F or 19 degrees C) for four weeks had a number of metabolic advantages, such as an increase in brown fat levels and improved insulin sensitivity .
However, none of the men taking part in the study actually lost any fat.
Japanese researchers report slightly more promising results. They found that six weeks of mild cold exposure (two hours per day at 17 degrees C or 63 degrees F) led to, on average, 1.5 pounds of fat being lost .
Which isn’t a lot.
Some of the subjects got better results than everyone else, losing around four pounds of fat. Others ended up gaining weight. And two hours of daily cold exposure is a lot different to 30 seconds spent in a cold shower.
In addition, the men taking part in the study were not following any kind of prescribed diet or exercise program. We know very little about how regular cold exposure will affect the results of someone who is training regularly and eating a sensible diet.
Will Turning Down the Thermostat in Your House Help You Lose Weight?
As well as cold showers, I’ve also seen claims that turning down the thermostat in your house can help you lose weight.
Experts say that because we spend so much time indoors, usually in warm homes and offices, your body doesn’t need to burn as many calories to keep you warm.
Their solution? Make yourself cold.
According to one doctor, turning down the thermostat from 24 to 19 degrees Celsius has been “proven to boost brown fat activation and burn about 100 more calories every day: an annual equivalent to 20 days of fasting.”
And there is some research to support the idea.
Dutch researchers, for example, found that when room temperature drops from a warm 22 degrees C to a cool 16 degrees C, test subjects burned an average of 170 additional calories per day .
What’s more, there is research linking the rise in obesity with a parallel rise in the typical thermostat settings in US and UK homes.
So it seems to makes sense, on paper at least.
But to me, it’s one of those “sounds good in theory but doesn’t actually work” type of ideas.
For one, most people don’t like feeling cold.
Turn down the thermostat in your house, and it’s probably not going to stay turned down very long.
Either that, or you’re just going to put on a warm jumper or sit under a blanket, eliminating any fat-burning benefits that turning down the thermostat might have had in the first place.
Other people you share a house with are also going to have an opinion on what the temperature should be.
Unless you have the persuasion skills of an FBI negotiator, chances are you’re not going to convince everyone who lives with you to be slightly colder than they want to be.
There’s another problem.
Being cold has been shown in various studies to have an effect on your appetite. So you might burn more calories by living in a cold house… but end up replacing them all (and more) simply because being cold makes you want to eat more than normal.
Why Being Cold Makes You Hungry
One of the big problems with exposing yourself to cold temperatures is that it tends to make you hungry.
In one study, immersing men in cold water for 20 minutes following a bout of treadmill running led to a 20% increase in calorie intake compared to a control condition .
Blood samples also show that cold water immersion led to changes in both leptin and ghrelin levels, two hormones that play an important role in controlling your appetite.
Here’s how the researchers sum up their findings
In summary, a short period of postexercise water immersion significantly increases ad libitum energy intake in the subsequent meal among young, trained men. This may be attributed, in part, to a tendency for lower levels of circulating leptin, together with higher active ghrelin after immersion in cold and neutral water, respectively.
University of Florida researchers report similar results . They got a group of men to exercise for 45 minutes at around 75% of their max heart rate in both neutral and cold water. The men were then allowed to eat as much food as they wanted.
Calorie intake after exercise in the cold water averaged 877 calories, which was almost 50% more than for the neutral temperature.
Even out of the water, exercise in the cold (8 degrees C or 46 degrees F) stimulates post-exercise food intake to a greater extent than exercise in a neutral (20 degrees C or 68 degrees F) environment .
Just sleeping in a cold room (19 degrees C or 66 degrees F) for a month has been shown to increase the desire to eat and reduce satiety, which reversed when the temperature in the room was raised .
To quote the study authors directly:
“Because the desire to eat heightened after cold acclimation, we cannot exclude the possibility that appetite stimulation could diminish metabolic benefits of BAT recruitment if it increases caloric intake in longer-term studies.”
In other words, you might burn more calories by exposing yourself to cold temperatures, but end up replacing them all because the cold leaves you hungrier than normal.
Studies show that cold water immersion can help relieve sore muscles , enhance the adaptations to endurance training , as well as accelerate recovery during periods of intense cycling training .
However, there’s no evidence to show that spending 30 seconds under a cold shower has any significant impact on your metabolic rate, and the idea that cold exposure has a big impact on fat loss is based on some very flimsy evidence.
Yes, being cold does burn calories. But it doesn’t follow that taking a cold rather than a warm shower in the morning, or exposing yourself to some other form of extreme cold, will help you lose weight faster. That’s because cold exposure also affects your appetite, so you may end up eating back the calories you burned.
All things considered, I’m not convinced that walking my dog on a cold winter morning wearing nothing but shorts and a vest is going to produce a change in body composition that’s worth the discomfort involved in doing so.