Cold vs. Heat: Which Temp Burns More Calories?

Everyone has their preferences for how they want to exercise. Some like to wear layers and turn up the heat when pumping iron. Others like to run for miles, no matter how cold it is outside. But have you ever given any thought to how many calories you’re burning when it’s cold or hot — and if one burns more calories than the other?

Sports medicine physician Matthew Kampert, DO, shares how temperature can affect physical fitness and which temps are best for your workouts.

Is cold or hot weather better for burning calories?

It takes a lot of energy — in the form of calories — to keep you alive. Even when you’re at rest, your body is constantly burning calories to do vital things like keep your heart beating.

It also takes calories to keep your core body temperature at about 98.6 degrees Fahrenheit (37 degrees Celsius). If your body gets too hot or too cold, it burns extra calories to get your core body temperature back to a healthy range. This process is called thermoregulation.

“The harder your muscles work, the more calories you burn,” says Dr. Kampert. “So, if you’re exercising in hotter or colder weather, your body has to work harder to regulate its temperature while you’re exercising.”

Both cold and hot weather can slightly increase the number of calories your body burns. But for most people, the difference is so small that it won’t have much impact on weight loss. It’s the workout itself that’s responsible for burning most of your calories.

Dr. Kampert explains how calorie burn changes in both cold and hot environments.

Burning calories in the cold

In colder environments, your body works to keep your core temperature from dropping. To do that, it first tries to conserve heat. If that’s not enough, it starts generating more heat. This process involves several different mechanisms, such as:

• Vasoconstriction: Your blood vessels narrow and send less warm blood to the surface of your skin to help reduce heat loss.
• Brown adipose tissue activation: Everyone has brown fat, a special kind of fat that burns calories to generate heat, helping your body maintain its temperature.
• Shivering: When you’ve got the chills, your muscles automatically burn calories and generate heat by rapidly contracting and relaxing.

“Your muscles require energy every time they move, even when it’s an involuntary action like shivering,” explains Dr. Kampert. “You may burn a few extra calories when you’re cold, but the increase is small and isn’t enough to make exercising in cold weather a weight-loss strategy.”

Plus, without proper protection and enough layering, long-term exposure to cold weather could lead to injury and impact dexterity, flexibility and muscle strength.

Burning calories in the heat

Some people intentionally exercise in the heat or wear extra layers to make themselves sweat more, thinking it will help them burn more calories. But sweating doesn’t always equal an increase in calorie burn. It’s simply your body’s way of cooling itself down through thermoregulation.

When your body overheats, it works to lower your core temperature to healthy levels. It does this primarily through:

• Vasodilation: Your blood vessels widen to send more warm blood to the surface of your skin, allowing heat to escape.
• Sweating: Sweat evaporates from your skin, carrying heat away from your body and helping prevent overheating.

“Sweat evaporates more easily in hot, dry environments,” says Dr. Kampert. “In humid environments, the air is already saturated with water vapor, so it becomes harder for your body to cool itself down and harder to exercise.”

Trying to make yourself sweat more by exercising in extreme heat or wearing heavy clothing isn’t an effective weight-loss strategy. Instead, it can increase your risk of:

• Dehydration
• Heat cramps
• Heat exhaustion
• Heatstroke

A better approach to working out in any temp

Working out in extreme temperatures poses significant risk for older adults, young children and others with a reduced ability to regulate body temperature.

Check in with your healthcare provider before exercising in cold or hot temps if you:

• Have cardiovascular disease
• Have diabetes
• Have obesity
• Take certain medications, like blood thinners

“If your goal is to burn more calories, the intensity, duration and consistency of your workout matter far more than the temperature of your surroundings,” stresses Dr. Kampert. “When exercising, focus on training safely and be prepared for inclement weather.”

Avoid wearing too many layers or accessories on your next cold run. Excess sweat can cool your body too quickly after exercising, making you feel colder. Instead, Dr. Kampert suggests wearing:

• A synthetic moisture-wicking base layer, like nylon or polyester
• An insulating middle layer, like fleece or wool
• A windproof or weatherproof outer layer

When it comes to the heat, stick to clothing that’s:

• Lightweight
• Light-colored
• Loose fitting

In either case, you want to stay hydrated and take things slow. If you feel dizzy or distressed, or if something doesn’t feel right, stop what you’re doing and head inside for recovery.

“Exercising in extreme temperatures increases the intensity of a workout, but it comes with its own set of risks and won’t increase how many calories you’re burning in any significant way,” reiterates Dr. Kampert. “If you’re looking to burn more calories, try progressing your workouts by increasing the amount of sets, reps or weight you’re lifting.”