However, it’s possible that, while brown fat might not help you shed the pounds, it could still boost your health in other ways. For instance, instead of burning calories, brown fat could help to improve metabolic health – the body’s ability to process and use energy from food effectively. People who have poor metabolic health are unable to clear glucose from their blood quickly, raising their risk of type 2 diabetes. Brown fat could act simply by taking up glucose from the bloodstream, or by secreting hormones that act on other tissues to regulate insulin sensitivity.

“In terms of whole-body energy expenditure, it [brown fat] probably does not play as large of a role in humans as it does in mice,” says Cohen. “So my personal feeling, based on the data, is that brown fat activation is not going to be a good means to treat obesity or to lose significant amounts of weight.” 

“However, the data is much stronger to suggest that activating brown fat might lower glucose levels and improve metabolic health. So, I think if there is going to be a therapeutic side to this, it’s much more likely going to be in treating the complications of obesity and ageing than in treating obesity per se.”

The shock of cold-water immersion causes the body to think it’s in danger

But how can we activate brown fat, and harness the superpowers it may – or may not – contain? One way is to expose yourself to cold, as uncomfortable as it may be. Think ice baths, cold water swimming, or cryotherapy chambers – a specialised device that exposes the body to extremely low temperatures for one to three minutes to promote healing and wellness. The shock of cold-water immersion causes the body to think it’s in danger, activating the fight-or-flight response. This releases the neurotransmitter noradrenalin, which binds to and “activates” brown fat cells.