How to lose weight with exercise. Don’t rely on the calorie counter on your fitness watch. Recent studies have shown that the calorie burn figures vastly overestimate the amount of calories burned with exercise.


As a Certified Nutritionist, I always point out that the key to weight loss is changing your diet. You simply cannot burn enough calories working out to lose any significant amount of weight. But, exercise is indispensable to health and when we are consistently exercising, we are also more likely to make healthier food choices.


How to Lose Weight with Exercise: Your Fitness Watch is Lying to You


Apple Watch, FitBit and other leading fitness trackers don’t measure how many calories are burned with any degree of accuracy. The manufacturers advertise that calorie counting as one of the main features of the trackers, but testing shows them to be way off the mark.



Study Shows Fitness Trackers Provide Inaccurate Calorie Burn Data



Researchers from the Stanford University School of Medicine found seven of the major fitness trackers on the market were unable to accurately measure energy expenditure, with averages off by as much as 93%. The most accurate device, the Fitbit Surge, had an error rate of 27%– researchers said the amount of error shouldn’t be more than 10%.


The study found men with darker skin tones and higher body masses were the most susceptible to inaccurate readings. The error rate surprised the researchers: “But the energy expenditures were way off the mark. The magnitude of just how bad they were surprised me.”


The research team evaluated seven devices, the Apple Watch, Basis Peak, FitBit Surge, Microsoft Band, Mio Alpha 2, PulseOn and Samsung Gear S2, on 60 different volunteers, including 31 women and 29 men.


The volunteers wore the while walking or running on treadmills or using stationary bicycles. The researchers measured the participants’ vitals with an instrument that measures the oxygen and carbon dioxide in the breath, the “gold standard” for calculating energy expenditure.


If your fitness watch tells you that you’ve torched 2,200 calories, on the low end it could be overestimating by as many as 600 calories. “The error depends on the type of activity you’re tracking,” says lead study author Anna Scherbina, “For activities like walking and sitting, the results are more accurate than for more intense pursuits, like spinning and running,” she explains. “The point is, you’re not burning as much as you think you are.”


Why are the Trackers So Inaccurate in Measuring Energy Expenditure?


No one knows for sure, why to calorie counts are so unreliable, but Anna Shcherbina reports that each device uses its own specific algorithm to measure calorie burn. Most likely those formulas make inaccurate assumptions for individuals.


“My take on this is that it’s very hard to train an algorithm that would be accurate across a wide variety of people because energy expenditure is variable based on someone’s fitness level, height and weight, etc.”


Fitness Trackers Do Measure Heart Rate Accurately


Six of the seven devices measured heart rate very accurately, with an error rate of less than 5%, and “performed far better than we expected,” according to Euan Ashley, a professor of cardiovascular medicine on the research team.
Heart rate, as opposed to energy expenditure, is measured directly and doesn’t need to be separately calculated, which is why they had higher rates of accuracy.


Click here for the Stanford University research.