How many calories the body burns is complicated science. The contributing factors range from height and weight to genes and fitness level. Two people who are seemingly the same in size and shape can use shockingly different amounts of energy doing the same exercise.
People used to think that the only way to lose weight was to eat less and run more. But things are not so black and white. Doctors now know that starving leads to the opposite effect and short workouts are exponentially more effective than an hour on the treadmill.
“In a study produced by American Council on Exercise (ACE) , the average calorie burn in a 20-minute workout was 272 calories, not counting the additional calorie burn due to the substantial anaerobic effort,” according to Angela Gallagher, Certified Group Fitness Instructor and Certified Personal Trainer.
Estimated oxygen consumption and how many calories burned aerobically was 13.6 calories per minute. However, anaerobically, the calorie burn was another 6.6 calories per minute. This brings the total to 20.2 calories per minute. “That's the equivalent to running a 6-minute mile pace,” she adds.
Whatever you do, know that you don’t have to break a sweat to prove that you are working hard enough. “This is a myth,” Gallagher says. “The reality is that sweating is not necessarily an indicator of exertion.”
Sweating is the body’s method of cooling itself. Many people associate it with burning more calories, but heat contributes to sweating, not necessarily the effort. “Those who don’t sweat easily shouldn’t discredit their efforts since it is possible to burn a significant amount of calories without pouring sweat,” Gallagher adds.
Many people choose swimming as an alternative to running. While it certainly is an effective full-body workout while keeping it easy on your joints, you're going to have to really swim hard if a super-high calorie burn is what you're after, Gallagher says. “Running at a 7 mph pace for one hour burns nearly 700 calories, while swimming at 50-yards-per-minute burns around 550 calories per hour,” she adds.