If you’ve ever tried hot yoga, you know that working out in the heat means sweat on sweat on sweat. Does it also mean you burn more calories? Yes, you’ll burn more energy in the heat while your body’s working overtime to cool itself down.

But don’t crank up the thermostat and jump on the treadmill just yet. Keep in mind that those extra calories prob won’t make a significant difference. It also puts you at serious risk of experiencing heat-related illnesses like heat exhaustion and heatstroke, which are no joke, folks. Here’s what you need to know.

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When you’re getting your exercise groove on, your body temperature rises to keep up with the increased physical demand. Your body’s an efficient machine, though. So, it has a built-in cooling system that produces sweat.

Sweat takes heat from your body to evaporate into the air. This helps keep your insides at a safe status quo between 97°F to 99°F (36°C to 37°C) at all times. A workout demands more of this natural cooling system.

How hard your body works at any given temperature depends on a few factors. The outside temperature, humidity, your fitness level, and a whole lot of other parameters come into play. For most people, once the temperatures reach 80°F (27°C), they’ll notice that physical exertion is a whole lot harder.

It works… but is it a good idea?

Hot yoga and spin classes may crank up the thermostat to 90°F (32°C) or more. While some exercise gurus might promote working out in extreme heat as a weight-loss method, it’s highly controversial for two main reasons.

  1. The human body adapts to changing conditions. It only takes about 14 days for your body to get used to the heat. After that, you’re no longer benefiting from that calorie-burning boost.
  2. Too much heat can be life threatening. Your body can reach a point where it produces more heat than it can get rid of. Then, you’re in danger of heat exhaustion or heatstroke, and that can be fatal.

Getting too hot for too long can put you at risk of many unpleasant and dangerous symptoms. Prevention is important, but you should also keep an eye out for early symptoms of dehydration and heat exhaustion if you’re working out in a hot environment.

Dehydration

Sweat keeps you cool. But if you’re getting rid of too much fluid without replacing it (like by drinking water) you could experience dehydration. Watch out because symptoms get worse the longer you go without water.

How to spot it

Symptoms include:

  • cold, clammy skin
  • dry skin
  • dry mouth
  • fatigue
  • constipation
  • dizziness
  • lightheadedness
  • increased thirst
  • decreased urination
  • headache
  • dark urine
  • rapid heart rate

What to do

Drink, drink, drink. In addition to drinking water, you may also need electrolytes to keep your body going. Sports drinks (at least those not loaded down with extra sugar) or drinks like Pedialyte can help replace other needed nutrients. But if you’re severely dehydrated, you need to seek medical attention ASAP for intravenous (IV) fluids.

Heat exhaustion

Think of heat exhaustion as the sign before heatstroke. It may not be as bad as heatstroke, but you need to act fast to turn it around. Heat exhaustion is a red alert situation where you need to get out of the heat, cool down, and get hydrated.

How to spot it

Symptoms include:

  • confusion/irritability
  • slow heart rate
  • heavy sweating
  • fever
  • vomiting
  • dizziness
  • fatigue
  • headache
  • nausea
  • decreased urine

What to do

Get out of the heat and start drinking water. You should also take off any unnecessary clothing, including socks and shoes. Apply cold compresses on the body to bring your temperature down.

Heatstroke

Heat exhaustion will progress to heatstroke if you don’t cool down. During heatstroke, you’ll stop sweating because your cooling system fails, and you lose the ability to cool your body. This is a situation that needs immediate medical attention.

How to spot it

Symptoms include:

  • confusion
  • slurred speech
  • hot, dry skin without sweat or profuse sweating
  • high body temperature, more than 104°F (40°C)
  • loss of consciousness

What to do

Take immediate action by cooling the body. Remove unnecessary clothing and apply cool compresses. Place cool, wet clothing on the head, neck, armpits, and groin areas. Get to a doctor right away for treatment.

Try to exercise at cooler times of the day. These times can include the morning or evening. Or, exercise in a temperature-controlled environment like the gym when outdoor temperatures are hotter than Satan’s house cat. It’s also helpful to wear appropriate clothing for the temperature, too. Moisture-wicking, breathable fabrics can make a difference.

Hydration helps. The temperature alone doesn’t guarantee you won’t overheat when you’re working hard. Always drink enough water before, during, and after your workout.

For moderate exercise, that means drinking 8 to 10 ounces of water an hour or so before working out. Then, shoot for 20 ounces of water during the workout. However, if you’re doing strenuous exercise, you may need 10 ounces every 10 to 20 minutes.

Keep in mind that higher humidity levels will make it easier to overheat even in lower temperatures. Your body can’t cool down if the sweat can’t dissipate.

It is possible to acclimate yourself. Your body can learn to function more efficiently in hot conditions, but it does that gradually, over a period of 7 to 14 days. Start by working out for a short period of time in hot weather. Over the course of 2 weeks, you can slowly increase the time spent exercising in the heat. This helps the body sweat and cool more efficiently.

Pay attention to how you feel. There’s something to be said for pushing through the pain, but there’s also wisdom in listening to your body. If you’re feeling overheated, slow down, cool down, and drink plenty of fluids.

We’ve established that cranking up the heat isn’t your best bet when it comes to burning more calories. How should you aim to get the most out of your workout? Check out these top tips.

  • Resistance training. Muscle burns more calories than fat, and there’s evidence that resistance training can increase your overall calories burned for the day.
  • HIIT training (with fewer reps). Use your time wisely with intense, short workouts. Try a traditional HIIT workout or spread your wings with a Tabata workout to change things up, stay intense, and burn extra calories.
  • Plyometrics. These power exercises light up your type II muscle fibers. These burn more calories in short, intense bursts.
  • Change up your workout. Your body will burn fewer calories doing the same workout day after day because it adapts. Change your workout every few days or weeks. Do different lifts, walk on an incline, change the range of motion, or add bursts of intensity to keep your muscles guessing.

  • You burn more calories in the heat, but it’s not the most effective (or safest) way to maximize your calorie burn.
  • Be careful and pay attention to the symptoms of dehydration, heat exhaustion, and heatstroke. These include excessive sweating, headache, dark urine, fever, fatigue, and an altered mental state.
  • If you must exercise in the heat, stay hydrated before, during, and after your workout. Let your body get used to the heat by exercising in hot temperatures for progressively longer times.
  • Increase your calorie burn in safer ways by adding resistance training, plyometrics, or altering the exercises or intensity of your workouts.