Feel the heat: ideal calorie-burning temperature for HIIT workouts revealed

The result of this 50-people strong study might surprise you (it sure surprised us)

perfect temperature to do HIIT for optimal calorie burn
(Image credit: Getty Images)

There are many reasons why people love HIIT workouts: they can help you lose belly fat, get fit and boost metabolism without having to spend hours working out. But there is one factor no one takes into account when planning their HIIT workouts: the temperature of the room you're exercising in. Is there an ideal room temperature that maximises weight loss and calorie burning? As it turned out, there is.

'Temperature specialist' Stelrad wanted to ascertain the perfect temperature for a fat burning workout. In its empirical experiment, the company recruited 50 volunteers, gave them Fitbits to measure heart rate (plus calories burned) and asked them to do the same 20-minute HIIT workout for eight days in different temperature conditions each day. Calorie burn was measured on the fitness trackers and the participants were asked to record if they felt their exercise performance was hindered by temperature.

Before we go any further, it's important to emphasise that wasn't a scientific study and therefore we should take the results with a pinch of salt. There was no control group and from what we can tell, the results were all self reported, apart from the heart rate/calories burnt, of course, as this data was most likely taken directly from the wearables. We also don't know the age/sex/weight etc. of the participants and it is true that larger people are likely to burn more calories during the same workout.

During the HIIT workout session, air conditioning and heating were used to create the desired daily workout room temperatures. The average calorie burn was worked out across the group of 50 volunteers by adding up their total daily calorie burn and dividing it by 50.

Here are the results:

Ideal calorie-burning temperature for HIIT workouts
Room temperature °CAverage calories burnt% of respondents who felt their performance was hindered by temperature-related discomfort
523384
1024056
152420
202528
2524364
3022986
3522188
4021998

hiit workout temperature

(Image credit: Reebok)

What does the above chart show us? For one and probably most importantly, higher workout temperature doesn't equal to more calories burnt. Although we tend to say we 'burn' calories, this doesn't mean our bodies need high temperatures to do so. According to the study, the best temperature to workout in terms of calorie burn is 20 °C. Conversely, the lowest calories burnt were at the highest temperature of 40 °C.

The second surprising fact is that gyms in the UK normally have their thermostats set between 16–18 °C, which is clearly not the ideal temperature for burning calories. We appreciate that increasing the temperature to even just a couple degree higher would cost more money for companies so it's understandable gyms like to keep their cool.

That 16–18 °C range is closer to the most comfortable temperature for workouts: when the room temperature was set to 15 °C, 0% of respondents reported temperature-related discomfort.

Temperature experts at Stelrad interpreted the results like so: “At a higher temperature your body has to work harder to keep your body cool, hence burning more calories. However, when you’re too warm, you are unable to workout at the same intensity. Therefore, it’s important to find the sweet spot where your body is warm and burning extra calories, but you can also go full throttle with your workout.”

Do you like home workouts? Have a look at the best HIIT workout gear guide, as well as the one on the best home gym equipment to make sure you don't invest in gear you won't end up using. If you like a bargain (who doesn't?), we have a roundup of the best Bowflex deals, best Fitbit Versa deals and best Fitbit Charge deals too. 

Matt Kollat
Matt Kollat

Matt is a fitness fanatic (a.k.a. fitness and nutrition writer) who's been rambling on about all things health and fitness for over two years now here at T3. His achievements include a short-lived fitness podcast called Fit Mentality Podcast and being a judge on the Fit&Well Awards 2021. In his free time, he works out at home, runs, cycles and loves a good ol' walk around the city. He writes about general fitness stuff, fitness tech, workouts, workout gear/equipment, nutrition and much, much more.