At the gym, Richard Little used to hop from one elliptical machine to another, trying to find the one that told him he was getting the best workout.
"I migrate to the machine that tells me I've burned the most calories," says the 44-year-old from Brandon, Man. But frustration would set in when he works out on the road. "I go to a different YMCA and I see a new piece of equipment and I try that and work my butt off for 45 minutes. I'm used to seeing 600 or 700 calories burned and this machine tells me I've burned 250."
Calorie counters on elliptical machines, treadmills, exercise bikes and other fitness equipment should be taken with a grain of salt, fitness experts say. Because the formulas they use are based on averages, it is impossible for them to be precise. And with some of the counters offering significant overestimates, their readings can often be misleading for people trying to lose weight and even hamper weight-loss efforts.
"Some people leave the gym and say, 'Well I just burned 800 calories, I can go eat a 400-calorie cheeseburger and I still have 400 calories to burn.' And that's not the truth. They haven't even burned 400 calories," says Elizabeth DeLeavey, a Fredericton-based personal trainer.
The formulas built by Life Fitness, a U.S.-based equipment company, are based on in-house studies that test a variety of users of different ages, weights and genders who undergo a VO2 test, which "translates in to a scientific equation that basically calculates the calories burned," says Bob Quast, vice-president of brand management and product development.
Calorie counters on the company's equipment are accurate to within 10 per cent, he says.
As recently as 10 years ago, however, many fitness equipment manufacturers were so keen to use calorie counters as a marketing tool that they were designed to offer grossly inflated estimates, Mr. Quast says.
A 20-minute workout on an older piece of home fitness equipment might say you have burned 1,000 calories, when "really it's probably about 200," he says.
The formulas used to produce calorie counters have now become much more scientific, he adds.
But even with newer equipment many trainers are skeptical about just how many calories a machine will say a user has burned.
"Sometimes they're 20 to 50 per cent overshooting the calories," says Iris Pinder, a personal trainer and owner of MultiSport Fitness, in Calgary. "That's a pretty huge discrepancy, especially for somebody who starts getting frustrated because they're not losing weight. It can be discouraging."
Even though he doubts the veracity of calorie counters, Mr. Little still occasionally indulges in willful ignorance.
"I feel better after the machine tells me I've burned 800 calories. I think I can afford that beer and those chicken wings," he says.
Of course, there are a number of factors that can skew the readout on a calorie counter, especially because most machines only require users to enter their age and weight.
"Age and weight are definitely important, but are you 250 pounds of muscle or are you 250 pounds of fat? What's your fitness level? If you're running and you're fit, you're running a lot more efficiently and you're burning a lot less calories actually than somebody who isn't as fit," Ms. DeLeavey says.
The counters are limited in other ways as well, Ms. Pinder says.
"If you stop moving on the machines, the majority of them continue to count the calories. So say if you jump off to the side of the treadmill to take a drink of water and get back on, the treadmill is still going so therefore it's still counting your calories," she says.
Russ Tupling, an assistant professor of kinesiology at the University of Waterloo in Ontario, says most calorie counters today are generally "pretty good."
"These equations that are used to estimate caloric expenditure are based on a lot of studies that have validated with direct measurements of calorie expenditure [how many calories a person is burning]" he says.
Still, users shouldn't expect them to be 100-per-cent exact, says Stephanie Dupuis, director of personal training at GoodLife Fitness.
"That feature does provide a rough estimate of the calories that someone is burning based on the average caloric burn rate of a person with a weight that they enter into the machine. So it takes into account averages, which is why you would want to take it with a grain of salt," she says.
But even so, calorie counters can be great motivation, especially for people who are just setting out to get in shape.
"It gives them a goal to reach," Ms. Dupuis says.
As for Mr. Little, he's found a way to make his calorie counter readout consistent, even if it can't be completely trusted.
Now, he says, "I try [to]use the same machine all the time."