Despite compelling research that states otherwise, there’s always the odd gym bunny that believes sweat is simply the tears of burning fat. So, it makes sense that the hotter it is, the harder your body works.

But that’s not quite the case according to Kamal Patel, director of supplement watchdog Examine. An extensive study by the organisation argues for a different approach to temperature regulation, and it’s bound to get the old school all hot and bothered.

The Science

Adding brains to the brawn is no easy task, yet Patel argues that cold crunches are more effective than hot-as-balls barbells.

“Nearly 50 per cent of calories are burned to maintain the body’s core temperature of 37 degrees Celsius. When it gets too cold, the body creates heat by shivering. This can multiply our heat production five-fold, and thus burns a tonne of calories.”

The advent of central heating has acclimatised humans to warmer temperatures, although we’re naturally built to tackle the cold with something called brown adipose tissue, more commonly known as brown fats.

“After some time, the body grows accustomed to shivering thanks to brown fats, which heat up the body – their sole purpose is to raise the body temperature, as opposed to regular white fats that store energy. Colder environments activate this brown fat, and extra calories are burned via the process of heat creation.”

The Method

Exposing yourself to colder temperatures before, during and after a workout can stimulate brown fats. But that doesn’t mean turning your lounge into the South Pole.

“Cold exposure at around 18 degrees Celsius is not that extreme. Further studies have shown that after a few days, subjects find the mild cold exposure less uncomfortable and shiver less, or not at all. Most adults can withstand eight-hour periods at this temperature.”

That said, there’s no single temperature that’ll guarantee optimal calorie-burning. “It’s impossible to predict the effects of cold exposure on any given individual, as studies have shown that energy expenditure after very mild cold exposure can range from a 12 per cent increase downwards.”

The Moves

If the body is forced to fight the freeze during a workout, it’s likely to burn even more calories. However, Patel only advises a low-intensity, steady-state cardio workout – commonly abbreviated to LISS – in such conditions.

“LISS moves are the most common exercises performed in colder environments, and also the safest. The cold can increase risk of injury if undertaking anaerobic, lifting or sprinting moves, and there’s little need for them either. Calorific expenditure gets much higher the colder it gets, so [walking, hiking or cycling at a moderate pace] is more than enough if body toning is your goal.”

The Green Light

As always with any major fitness regime switch-up, it’s worth consulting a doctor beforehand and exercising caution. Cold therapy can trigger undiagnosed Raynaud’s phenomenon – a condition that affects the blood supply to certain parts of the body – or other circulatory problems.

“Mild cold exposure may be a simple option for weight loss, but it’s not something to be trifled with. Don’t do something stupid, such as sleeping outside in your underwear when it’s freezing, or fainting in an ice bath.”