It's a bone-chilling discovery.

Ice baths - beloved by millions in wellness circles for their supposed health benefits - may be making you fat.

Also known as cold plunges, they have been linked to lowering stress, soothing muscles, boosting mental health and even fat loss.

But new research suggests that ice bath sessions could actually cause people to get fatter in the long term, by causing them to overeat. 

In a study looking at how water temperature impacts appetite, participants were submerged in three pools up to their sternums with the water heated differently in each bath (61 F, 79 F, 95 F).

Following a 30-minute bathing session, the volunteers were offered unlimited portions of pasta.

Repeated trials of the study showed that participants who were in the coldest pools consumed more food than those who bathed in warmer temperatures.

In some instances, the cold water plungers consumed more than 200 calories more than their warm water peers.  

Serving up a bone-chilling shock to the system, cold water plunging has become a wellness trend beloved by millions for its supposed health benefits (stock image)

Marie Grigg, who led the study as part of her PhD studies looking at exercise and nutrition science at Coventry University in the UK, told the Daily Mail that it is not clear why colder water temperatures trigger a bigger appetite. 

'Although the exact mechanisms are yet to be elucidated, further research is required to identify if the after-drop in core temperature is a potential mechanism responsible for compensatory food intake post cold-water immersion,' she concludes. 

The scientists add that with cold water immersion becoming popular, their findings have implications for people who are trying to incorporate it into a weight loss regime. 

It could also have an impact on clinicians developing weight-loss plans.   

New York-based personal trainer Natalya Alexeyenko told the Daily Mail that she has some ideas as to why cold water could trigger a rumbling stomach.  

'During cold water immersion, the body kicks into thermoregulation mode, which is when the blood vessels constrict, the heart rate goes up, and your metabolism speeds up to maintain core temperature,' the fitness expert said.

She then explained the after-drop that happens after someone gets out of the water: 'the internal temperature keeps falling briefly as cold blood returns from the skin to the core.

'That's when the body sends a strong physiological signal to refuel, even if you're not consciously hungry... the body is essentially saying, 'We need energy now.'' 

Alexeyenko says the 'tricky part' is that people often reach for high-calorie, fast-energy foods after cold water plunging, which can lead to fat gain if you're not mindful. 

To avoid adding unwanted pounds, she suggests 'refueling smart' with complex carbohydrates (sweet potatoes, quinoa), lean proteins (eggs, fish, protein powder) and leafy green vegetables.

These are all low-calorie foods that help people feel full without consuming too many calories. 

'Warm drinks help too,' Alexeyenko adds. 

Health experts have pointed to other potential downsides of cold water plunging and ice baths.

Firstly, it has recently emerged that these practices could get in the way of how your body grows muscles, and can make it harder for you to get bigger and stronger in the long term. 

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'Performing cold water immersion after exercise is probably harming your gains,' Dr Rhonda Patrick, a fitness educator who studied biomedical science and nutritional biochemistry, said.

Dr Patrick shared in a post on X that the chilling effect can actually reduce the amount of proteins your body makes after a workout.

During weight lifting, muscles tear. The body patches those tears with proteins, which over time make muscles bigger and stronger.

The less proteins the body makes, the less the muscle is reinforced and grown.

'People looking to improve their muscle conditioning should reconsider using cooling as part of their recovery strategy,' she said, adding you should avoid doing cold plunges on the same day that you lift weights or do calisthenics. 

There are also more serious concerns around the trend, including an increased risk of hyperventilation and hypothermia that could be life-threatening.

This is because, when the body is suddenly exposed to cold water, we almost instantly take a deep breath as the body demands oxygen.

This is followed by hyperventilation - a rate of rapid breathing 10 times faster than normal.

Sudden exposure to cold water also dramatically increases the risk of cardiac arrest as the body desperately attempts to slow the amount of heat escaping to keep the vital organs functioning as normal.

At the same time, heart rate increases, putting the organ under immense strain, creating a potentially fatal spike in blood pressure.

As of 2024, 11 people are thought to have died as a result of cold water exposure.

However, researchers in Canada recently found that cold plunges can help ward off disease and slow down biological aging.

The researchers tracked 10 healthy men who took the plunge for 60 minutes a day over the course of a week.

Overtime, analysis of blood biomarkers showed there was a reduction in inflammation and cellular damage.

Dr Kelli King, who lead the study, said, 'It's like a tune-up for your body's microscopic machinery.'

He suggested that the stress response from the cold water was responsible for the boost in cell function.

New York-based personal trainer Ben Unger also believes the pros of cold water plunging outweigh the cons, and he says he has seen a benefit to his health. 

Plunging into cold water. Thanks to Wim Hof, (pictured) nicknamed the iceman for his freezing feats, cold water dips have become increasingly popular

In terms of how to prevent weight gain, he told the Daily Mail that, 'At the end of the day, though, it comes down to self control and keeping track of your caloric intake. 

'If one is able to withstand the hunger pangs and stay in their daily calorie range, the benefits of ice baths outweigh any negative impacts it may have.'

Alexeyenko says those who are interested in getting into cold water plunging should 'start slow'.

'I would recommend starting with 30 seconds [to] a minute of immersion and to gradually build up from there,' she said.

'It's always important to have a proper warm-up routine afterward, too, with some dynamic stretches, like arm circles or leg swings.'