Wearing an ice vest helped obese individuals lose body fat, research found. In a study jointly conducted by Leiden University Medical Centre and the University of Nottingham, 47 participants with obesity or overweight were split into two groups. Half wore a cooling vest and waist wrap for two hours each day over six weeks. The cooling packs inside the vest were maintained at 15°C. That group lost an average of 0.9kg of almost pure body fat, while a control group that did not use the vest gained 0.6kg over the same period. The findings were presented this week at the European Congress on Obesity in Istanbul.
How cold exposure triggers fat burning
The mechanism behind the weight loss centres on brown adipose tissue, or “brown fat” — a type of fat that burns calories to generate heat. Unlike white fat, which stores energy, brown fat acts as the body’s internal heater. Cold exposure is the most powerful known trigger for activating this tissue. When the body senses cold, the sympathetic nervous system releases noradrenaline. This neurotransmitter binds to beta-adrenergic receptors on the surface of brown fat cells, setting off a chain of events that breaks down triglycerides and releases fatty acids. Those fatty acids then activate a protein called uncoupling protein 1 (UCP1) inside the mitochondria of the brown fat cells. UCP1 essentially uncouples the cell’s energy production from its normal cycle, allowing the mitochondria to burn calories directly as heat — a process that consumes body fat stores.
“This is one of the first studies looking at the impact of cold exposure over a prolonged period of time, involving people with overweight and obesity,” said Dr Mariëtte Boon, the study’s lead researcher at Leiden University Medical Center. “We know that exposure to cold temperatures prompts the body to activate brown fat, a type of fat that burns calories to produce heat. We also know that exposure to the cold activates skeletal muscles. These also generate heat, amongst others via shivering, to raise the core body temperature.”
Researchers at Leiden have previously identified that stimulation of a specific receptor — the beta-2 receptor — can activate brown fat, and they are exploring whether targeting this pathway could offer new treatments for diabetes and cardiovascular disease. The current study was jointly funded by the Dutch Heart Foundation and the British Heart Foundation. The broader implications of brown fat activation are being investigated for metabolic health, including its potential role in managing obesity, type 2 diabetes and cardiovascular conditions. Studies suggest daily cold exposure may have beneficial effects on lipids, glucose and inflammation, all of which are protective factors for heart disease.
Dr Boon is now conducting a separate study to see whether cold showers could produce a similar effect. That research involves 34 women in the Netherlands who will take a 90-second shower on the coldest setting every day. “We hope people can find a method of cold exposure that works for them and fits into their daily routine,” Dr Boon said.
Celebrity endorsements and expert caution
The idea of using cold exposure for health benefits is not new. Several high-profile figures have promoted cold-water swimming and ice baths. The Princess of Wales has spoken about the benefits of cold swimming for wellbeing and stress management, and Prince William has also taken up the practice. David Beckham has frequently shared his use of ice baths as part of his self-care routine. The “Wim Hof method,” which combines cold exposure with breathing exercises, has gained a substantial following.
Professor Helen Budge of the University of Nottingham, a co-leader of the ice vest study, said: “Daily cold exposure activates brown fat, which uses body fat stores to produce heat. It is our hypothesis that cold showers and cold swimming could have the same effect [as wearing a cooling vest].” However, she noted that the methods are not directly comparable. “The cooling vest is a much longer period of exposure than the shower.”
The vests themselves have been designed for everyday use. “They have been made for everyday use. There are certain occupations which already use them such as the construction industry in summer,” Professor Budge said. “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.” Cooling vests are already available on the market at various price points, though the researchers stress that the key is consistent daily use.
Despite the promising findings, experts urge caution. Cold exposure can increase blood pressure, heart rate and blood clotting, which may pose risks for individuals with pre-existing cardiovascular conditions. Anyone considering adopting cold showers, ice baths or cooling vests as a weight-loss strategy is advised to seek medical advice first.
