Wearing a vest laden with ice packs or taking a cold shower every day could help people lose weight, researchers say.
A trial involving 47 overweight or obese adults found daily exposure to cold temperatures led to significant fat loss within weeks.
Experts believe this is partly due to a type of tissue called ‘brown fat’ which is activated by cold temperatures and helps to speed up the rate at which the body burns calories.
They said daily cold exposure could one day be used as a ‘simple and inexpensive’ addition to weight loss plans.
Future research will examine cold showers, cold plunges and cold swims, which are popular with celebrities and royalty such as Harry Styles, David Beckham and Catherine, Princess of Wales.
She previously revealed: ‘As a family, we are very active. Personally, I love swimming. Cold swimming, the colder [the water] the better.’
In the current trial - the first of its kind - half the participants were asked to wear an ‘ice vest’ every morning for two hours while continuing their daily activities.
The gilet-style vests are worn on top of a t-shirt and contain pockets for gel-filled ice packs, which are chilled in the fridge or freezer and cool the core body temperature.
Wearing a vest laden with ice packs or taking a cold shower every day could help people lose weight , researchers say.
They maintain a temperature of 15C and are already used by construction workers or motorcyclists on hot days to help stay cool and protect against heat stroke.
Over a six week period, those who used the vest lost an average of 0.9kg (2lb), made up almost entirely of body fat, which the researchers described as ‘really exciting’.
In contrast, the control group did not lose any weight and put on an average of 0.6kg (1.3lb), according to findings presented at the European Congress on Obesity, in Istanbul.
It is the first real-world study to investigate the effect of the cold on weight loss in overweight people.
While the weight-loss was small, experts said it was significant and could not be accounted for by increased exercise as the participants had their activity levels monitored with fitness trackers.
The team, involving scientists at the University of Nottingham and the Leiden University Medical Center in the Netherlands, are now conducting a separate study of cold showers involving 34 women.
Half will be asked to turn their showers to the coldest setting for 90 seconds every morning.
The research team, jointly funded by the Dutch Heart Foundation and the British Heart Foundation, are investigating how the cold temperatures could reduce obesity, inflammation and prevent heart disease.
Over a six week period, those who used the vest lost an average of 0.9kg (2lb), made up almost entirely of body fat, which the researchers described as ‘really exciting’.
While there has been a ‘wellness’ boom in cold water swimming and cold plunges in recent years, there is still very little data on the health benefits of cold exposure.
Professor Helen Budge, from the University of Nottingham, said: ‘Mild cold exposure - wearing a cooling vest for a couple of hours each morning - was found to lead to weight loss.
‘This study is important because it has shown a reduction in fat mass. It is really exciting.
‘It offers another lifestyle choice for people wanting to lose weight and is important for health.
‘It could help with heart disease.
‘Daily cold exposure activates brown fat, which uses body fat stores to produce heat.
‘The aim of the study we are currently undertaking is to help add to the lifestyle choices people have to help prevent heart disease.
‘It is possible that wearing a cooling vest trains brown fat to be more active and has a healthy effect on lipids, glucose and inflammation in the body.
Catherine, Princess of Wales, has previously revealed her love of cold water swimming, saying 'the colder, the better'.
‘All those things are preventative in cardiovascular disease.
‘It is our hypothesis that cold showers and cold swimming could have the same effect.’
Lead researcher Dr Mariëtte Boon, of Leiden University Medical Center, added: ‘The participants found the vest comfortable to wear.
‘Vests like this can be worn at home and so cold exposure could be a simple and inexpensive addition to lifestyle strategies for weight loss such as healthy eating and physical activity.’
Dr Boon said cold exposure helps increase the number of calories people burn even before they start to shiver.
Cold plunges and cold water swimming have soared in popularity in recent years in the UK, driven by the popularity of the ‘Wim Hof' method involving plunges in icy lakes.
It was even the subject of prime time TV series ‘Freeze the Fear’, which was presented by Holly Willoughby and saw celebrities take on cold-water immersion challenges.
Ice baths - traditionally used by high-performance athletes - are increasingly popular among health conscious young adults due to perceived health benefits.
Brass Monkey, a company that installs ice baths at gyms and houses in the UK, said its sales have ‘doubled year on year’ adding that ‘cold water immersion has found a home in mainstream fitness environments’.
Other potential benefits of cold exposure include increasing the metabolism, soothing sore muscles and helping to cope with stress.