Is it possible to detect calorie burn with Wearables?

Wearables are devices that are worn on or near the body and are said to measure information concerning bodily functioning.  They have become very popular, giving feedback to the wearer of what is going on in his body.   It is a popular and expanding field of technology and more people are becoming interested in using these “activity trackers”. 

There is a lot of hype concerning these devices and the power of these technologies, particularly by those in Silicon Valley.  However, how accurate are these Wearables in really measuring calorie burn?

These apps and other devices proclaim to be very accurate in determining the numbers but can we really rely on them or are we taking a shot in the dark, like playing for online slots.

Below we get the opinion of some of the top experts in the field as to how accurate they really are.

Expert number 1

According to Michael Snyder, Chair of the Department of Genetics and Director of the Centre for Genomics and Personalized Medicine at Stanford University, the answer is “in some cases yes, in others no”.   He argues that they do work but they are far from perfect.   For instance, activities that don’t use accelerometers cannot be measured. They will likely measure calories burned when running on a treadmill but will do less well when measuring calories while using weights.  Snyder says “so much of calorie burn has to do with your intrinsic metabolism, which a wearable wouldn’t be factoring in”.  

When performing some activity that is increasing your heart rate, it is likely that these wearables will hone in on it and measure it.   However, these wearables will not ascertain the difference between how and why the calories were burned. Meaning, increased heart rate through the physical activity or increased heart rate through stress.

In order for these devices to be more reliable in providing information about calorie burn they need to be attuned to each individual wearing the device.  The device would need to be aware of how much energy the person uses when doing each specific activity.   The future does look promising though with more sophisticated devices being able to measure things like respiration and therefore able to distinguish different types of activity.  However, we are not there yet.

Expert number 2 

Albert Titus is a professor and Chair, of Biomedical Engineering at the University of Buffalo.   He says that “Our bodies expend energy continuously.  The term “energy expenditure” can also be thought of as “burning calories” in this context”.    The amount of energy we use up doing activities like walking, running, jumping or only sitting around is important in order to understand the whole picture.   Knowing this can show us how effectively the body is utilizing food and if you are using up more calories daily than you are taking in to your body.

Wearables to provide information about how many calories the wearer does burn. But establishing the calories burned is not an exact measurement, and there are a number of factors involved which vary from individual to individual.  “Studies indicate that the energy expenditure reported by all wearables deviates from “gold standard” measures of energy expenditure by significant amounts.  And generally, whether wearables under-estimate or over-estimate the amount of calorie burn depends on the wearable, the activity, and rate of that activity, which further confounds things.”

It seems that wearables have not yet reached the level of sophistication needed for use in monitoring the burning of energy for medical reasons or for purposes of athletic training.

If you are looking for a general guide as to how much energy you burn daily and to compare that over time, then wearables are a useful tool and may be a good motivation to become more active.   Just don’t rely on the accuracy of the numbers.

Wearables are improving all the time, with new versions coming onto the market all the time.  These new versions allow you to enter different kinds of activities which help to make them more accurate.   “The more customizable the wearable is to the individual user, the better the calculation should be”.   Studies will need to be made on the newer versions to test if they are better than the older versions at measuring the amounts of energy burned.

Expert number 3 

Edward Sazonov is a Professor of Electrical and Computer Engineering at the University of Alabama.   His research includes wearable devices and methods of biomedical signal processing and pattern recognition.   He says that “The accuracy of wearable devices that measure energy expenditure varies greatly.”

The most important elements are the sensors and algorithms.  An accelerometer which is a device that is used to measure the entire body’s movement, is currently the most common sensor used.  For example, an accelerometer is used to ascertain whether a person is walking or running and to count their steps. 

However, this type of sensor does not pick up all types of physical activity. For instance, if the accelerometer remains stationery during the time of the activity, the exercise will not register on the sensor. An example is when doing push- ups, with the person wearing the tracker on their wrist. 

Another sensor often used is the heart rate sensor. By measuring the heart rate, you can get a clearer picture of the intensity of the activity and the amount of energy used.

“Research grade energy expenditure monitors may include additional sensors, such as body temperature, air temperature, temperature flow, perspiration, galvanic response, barometric, and other sensors.    These sensors paint a more complete picture of the activity being performed and potentially improve the accuracy of the monitor.

Another key element in terms of accuracy is the algorithm used.  They may be simple algorithms, like the more steps taken, the more calories expended, or very complicated like “the algorithms that we develop and test…may include recognition of the physical activity as the first step (such as sitting, standing, walking, cycling, driving, etc.) and then the estimation of the energy expenditure using a model specific to that physical activity. 

For consumer-grade wearables, these algorithms are often a black box owned and carefully guarded by the company.  Over the past years, several research studies have shown that the accuracy of wearables varies dramatically in comparison to a highly accurate reference measurement….one should be keenly aware of no-name monitors that frequently fake both the sensors and energy expenditure calculation algorithms”.  

To conclude 

There is not one unanimous answer to the claims of accuracy.   It really depends on the device in question, the kind of activity it is measuring and the algorithms being used. However, accuracy is improving all the time with new sensors being introduced and the development of better algorithms. In comparison, the accuracy of physical activity measurement by a modern wearable is much higher than the accuracy of measuring when, what and how much we eat.

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