Does Sweating Burn More Calories?

Many people finish a workout drenched in sweat and may assume that they’ve burned more calories than someone whose shirt stayed dry. But do you really have to sweat buckets in order to lose weight?

Before you throw on heavy clothing or sit in a sauna in hopes of shedding extra pounds, sports medicine physician Matthew Kampert, DO, explains what’s really happening when you sweat and what it does (and doesn’t do) for calorie burn.

Do you need to sweat to lose weight?

You don’t need to sweat to lose weight, and sweating doesn’t necessarily mean you’re burning more calories.

While sweating and calorie burning often happen at the same time, they’re two very different processes:

Sweating itself requires very little energy. It’s your body’s way of preventing itself from overheating. When your body temperature rises — from vigorous exercise, hot weather or a fever — millions of sweat glands are activated. As sweat evaporates from your skin, it carries heat away from your body.

Calories are burned whenever your body uses energy, even at rest. That energy powers everything, from your heartbeat and breathing to your brain and muscles.

“Every movement you make requires energy,” says Dr. Kampert. “Your body gets that energy by breaking down carbohydrates and fat from the food you eat and the energy stored in your body.”

During exercise, your muscles burn through stored energy to keep you moving. The harder your muscles work, the more calories they burn and the more heat they produce. You start sweating because your body needs to cool itself down.

“If your body can’t get rid of that heat, your core body temperature continues to rise, affecting your performance and increasing your risk of heat-related illness,” he continues.

Think of your body like a car engine. Burning fuel creates power, but it also generates a lot of heat. Just as a car relies on its cooling system to keep the engine from overheating, your body relies on sweat to cool itself down.

In other words, burning calories can make you sweat, but it’s the calorie burn — not the sweat — that helps you lose weight.

Do you burn more calories when you sweat during a workout?

Not necessarily.

“During a hard workout, you often burn more calories and sweat more, but the increased calorie burn comes from your muscles working harder, not from the production of sweat,” clarifies Dr. Kampert.

Running in cool weather, for example, may burn hundreds of calories with relatively little sweat. It’s the act of running, not sweating, that helps you lose weight.

Can saunas help with weight loss?

Saunas make you sweat, but they don’t significantly increase fat burning. Most of the weight lost in a sauna is temporary water loss that returns after you’re rehydrated.

“Saunas may have cardiovascular and recovery benefits, but they shouldn’t replace regular physical activity,” stresses Dr. Kampert.

Can you still burn calories with no sweat?

You can burn calories even if you’re barely sweating.

How much you sweat isn’t a reliable measure of how hard you’re working or how many calories you’re burning. In reality, how much you sweat depends on factors like:

• Genetics
• Body size
• Fitness level
• Age
• Clothing
• Humidity
• Environmental temperature

Why do you lose weight when you sweat?

After a long or difficult workout, most of the immediate weight you lose is water weight.

“Sweat consists primarily of water and electrolytes,” explains Dr. Kampert. “Once you rehydrate, much of that weight returns.”

Actual fat loss occurs over time by maintaining a calorie deficit — or burning off more calories than you’re consuming in a single day.

“Generally speaking, losing one pound of body fat involves a deficit of 3,500 calories,” he adds.

Burning calories is hard work

If your goal is better health or weight loss, focus less on how much you’re sweating and more on how you’re feeling when you’re exercising on a regular basis. Your body composition changes because of the work your muscles are doing, not because of the sweat on your body.