Does sweating mean you are burning more calories?
WHEN it comes to exercise, there's nothing quite as satisfying as drenched pits and a dripping forehead. But does a sweat-soak shirt equal a better workout?
THE SCIENCE OF SWEAT
As your muscles generate heat during exercise, and your core body temperature rises, your body triggers a cooling process - sweating. Our sweat glands are designed to pump fluid (mainly water, salt and other electrolytes) through the skin to evaporate into the air, taking a heap of body heat with it. Of course, every person is different. Some people are natural sweaters - usually due to overactive sweat glands - and others can stay dry as a bone.
Apart from your genes, level of fitness or gender, the rate at which you sweat depends on two things: the environment (i.e. temperature) and your metabolic rate (which is determined by how hard you are exercising).
THE LINK BETWEEN SWEAT AND SUCCESS
While it's common to assume that the more you perspire, the more calories you burn, there's actually little correlation between the two. Consider this: If you run on the treadmill in an air-conditioned gym, you'll most likely sweat less compared to pounding the pavement in 30-degree heat. Granted your body has to work slightly harder to keep you cool running outdoors, it won't drastically elevate your metabolism. In fact, you may end up burning less energy instead. This is because being hot makes exercise feel harder, so you may exert less effort and fatigue quicker than when working at lower temperatures
WHAT ABOUT FAT LOSS?
There's a good chance that if you stepped straight on the scales after both instances (indoor vs. outdoors), you'd be slightly lighter after the outdoor run. Does that mean you've burned more fat? Not quite. It means you've lost more fluid through sweat - so you're seeing a temporary loss in water weight (not fat). As soon as you replenish your fluids, your weight will even out again.
WHAT REALLY MATTERS WITH CALORIE BURN?
There are two key factors that determine an effective calorie burn: duration and intensity.
As a guide for getting max workout results, current Australian physical activity guidelines recommend 150-300 minutes of "moderate" intensity physical activity or 75-150 minutes of "vigorous" activity a week. As for someone trying to keep their weight in check, guidelines recommend adults increase to 300 minutes (five hours) or 60 minutes of moderate intensity activity on most days of the week.
Forget stressing about your sweat. Just keep moving. Regular exercise (of any kind) along with a balanced diet is a sure-fire way to achieve and maintain a healthy weight, not doing everything you can to sweat more.
Kathleen Alleaume is a nutrition and exercise scientist and founder of The Right Balance. Follow her @therightbalance