It went from blazing hot to pleasant to near freezing in Texas in a matter of about a week. This was after a not quite so hot summer and one of the coldest winter’s we’ve had in a very long time. To top it off, restrictions from the COVID-19 Pandemic are pretty much lifted everywhere which means people are flocking back to the gym. This got me thinking about whether it is better to work out in the heat, cold, or somewhere in the middle when it comes to the goal of burning calories and fat. As you would probably guess, the answer is far from straight forward, and probably for the best, added benefits from working out in the heat or cold are typically temporary.
When it comes to working out in the heat, your body has to work harder to regulate your temperature and cool you down. As you continue to work out, your core temperature will rise, and so your body will burn more calories in an effort to keep you cool. There are three important factors to consider when working out in the heat.
Most of the weight lost during a workout in the heat is water weight lost from sweating. This is a very temporary weight loss, and you’ll likely won’t see a difference on the scale after you rehydrate.
Your body quickly adapts to working out in the heat (within 7 to 10 days). This means that the extra calories burned in an attempt to keep you “cool” won’t be there for long unless you keep increasing the temperature which may not be possible or safe.
Working out in the heat can be exhausting and may affect your performance. A planned 1-hour run during the heat of the day may turn into a 30-minute jog as fatigue sets in. Group exercise classes in the heat may mean you need to take longer or more frequent breaks or that you are unable to push yourself as hard as you’re normally able to in cooler temperatures.
What about working out in the cold? I’m not talking about a gym that has the A/C and fans blasting, but rather the shivering when standing still, see your breath cold? Does that burn more calories? Sort of. Much like when working out in the heat, when working out in the cold, your body has to work harder to regulate your body temperature. In theory this means more calories burned; however, that increased calorie burn is short-lived. As you start working out, your body temperature will naturally rise and the added calorie burn from shivering goes away. To keep the calorie burn higher while in the cold, you would need to stop exercising and let your body work to keep you warm by shivering. This isn’t very fun, and studies have shown that participants kept in cold environments for a full day only burned an extra 150-200 calories. That’s a whole lot of misery for not much added benefit. The biggest upside to working out in the cold is your ability to push yourself harder or longer. As your core temperature rises your body doesn’t have to work as hard to cool you off, and you can increase the intensity and/or the duration of your workouts.
So what is the best option for burning more calories during your exercises? If the goal is simply to burn more calories in a set period of time, heat may be the best option, but there are drawbacks as mentioned before in addition to safety concerns such as dehydration or heat exhaustion. If your goal is to burn more calories while doing as little as possible, submerging yourself in an ice bath may be the option to go, but that is not going to be very fun. If you live somewhere that gets hot in the summer, acclimatizing to the heat will make your summer workouts more enjoyable. You can then look forward to a likely improved performance as the temperatures cool. For longer endurance efforts, slowing down, staying hydrated, or working out indoors may be a better option to get the most from the workout.
