Calorie counting tools are becoming increasingly popular. They are available as part of many fitness apps, on heart rate monitors, and most commonly, they are attached to cardio machines that adorn our basement as well as the gyms we frequent. But, how accurate are they?
In two words: not very. Do not be completely disheartened, though, as there is more to the story.
The accuracy of your calorie counter is impacted in part by how much information you make available to it. The more info you provide, the more accurate the results will be. Data like height, weight, age, gender, and heart rate can all improve the accuracy of your calorie measuring tool of choice. If your elliptical does not ask you for the aforementioned data, or if you choose not to provide it, it will make some assumptions for you. The equations that these devices use vary somewhat depending on the manufacturer, but most use statistical averages (often based on a 150 pound young male). Therefore we recommend that you provide as much data as you can.
Unfortunately, even if you provide all the data your particular device asks for there will be some critical gaps that will impact its ability to accurately estimate your caloric expenditure. Metabolism is a very unique and individual thing; as such it is hard to estimate accurately. In addition to the variance caused by questions that are answered easily (age, gender, height, and weight), variables like body composition, the time and structure of your last meal, as well as even your stress level can have a dramatic impact on your metabolism.
Also it is worth mentioning that some companies have been known to intentionally provide positively-skewed data, assuming that the more calories you perceive to burn, the more you will enjoy (and recommend) their product… just something to consider.
Ultimately, you cannot really trust the calorie readings on your cardiovascular equipment. However that does not render the data is useless; rather it implies that you should be careful how you use the readout to make decisions. Since the estimates are largely inaccurate and vary from machine to machine, it is probably not a good idea to compare what you burn on the treadmill with what you burn on a stationary bike in order to decide which machine is more effective. The same goes for creating comparison between individuals – what a machine tells you and what it tells your friend may not be the same, and that says nothing about you or your friend’s level of fitness. Above all, do not estimate your weight loss expectations, or reward yourself with calorie-dense foods based on the readings provided by your calorie measurement device (not that using food or food-like substances as a reward is a good idea anyway).
What you can use these devices for is a measurement of relative intensity and/or performance. If you are using the same piece of cardiovascular equipment every time you work out, the calorie’s burned readout can help you compare your performance from day to day. This will allow you to set goals relative to your previous workouts, and can be a good way to push yourself to work longer and harder.
Above all, remember that cardiovascular exercise is aptly named, as it primarily impacts the function of your cardiovascular system. The road to body composition improvement rolls through the kitchen and the weight room. The low intensity, long duration work you put in on the elliptical is mainly for your heart, blood, blood vessels, and lungs. If you are headed to the treadmill with the idea of burning calories on your mind, you are missing the point.