Weighing the Benefits of Fitness Trackers

Nearly everyone and their grandmother is wearing a fitness tracker nowadays.

Whether wrapped around your arm, clipped to your belt or on your phone, devices can measure a plethora of health-related activity. They're mostly used by those who wish to become healthier through weight loss, increased activity or both.

But some of these technologies may not be as accurate or produce the results we want. There are several smartphone applications that measure everything from steps to sleep, all with varying levels of accuracy.

In fact, gold standard randomized controlled trials have not found that fitness trackers improve health. Let's delve into the accuracy and effectiveness of several health technologies.

A guesstimate is not a measurement

As a dietitian, one of the first things I recommend to someone trying to lose weight, regardless of their resources, is to track everything they put in their mouth.

Whether it is done via a smart device or in a paper journal, self-monitoring is critical for behavior change and health success. Self-monitoring in the nutrition world consists of recording dietary intake and bringing attention to the behavior the individual intends to change, like overeating.

Smart device applications offer many user-friendly features such as barcode scanners, recipe generators and some even allow you to take photos of your food to estimate calories.

But user error can be plentiful, especially since most applications allow users to input foods to a public database without verification. User error also includes failure to use food scales or measuring cups, oftentimes resulting in incorrectly estimating servings and calories. Knowledge gaps and misremembering food intake also serve as shortfalls for nutrition apps.

But the motivational uses, for many people, can outweigh the shortfalls.

Wearing a tracker is not exercise

Like nutrition, self-monitoring exercise can be helpful in facilitating behavior change.

However, whether wearing a fitness tracker promotes behavior change still carries a big question mark. Many researchers have found that simply wearing the trackers does not produce a change in health. But motivation can be enhanced by competitions and financial incentives.

The best step counters use GPS triangulation, and the estimated error is between 5-7 percent. When it comes to accuracy of calories burned, even the best devices can be off by 27 percent, with the least accurate as high as 90 percent. Since the calculation of the device is based on gender, measurements, fitness level, etc., it is very difficult for consumers to get an accurate calculation.

This does not mean that fitness trackers don't have great promise in the future, but more research needs to be done to determine how their usage can improve health.

Heart rate devices are most useful

Though fitness trackers don't show great promise in the accuracy of calories burned, heart rate devices certainly do, most measuring correctly within five percent.

There is limited evidence that knowing your heart rate actually makes you healthier.

It will help track progress though. Those new to an exercise program can measure their resting heart rate and measure it four to six weeks later to see if their fitness has improved.

Another possibility for those attempting to manage stress is to see how various stress relieving techniques help stabilize heart rate.

It could be helpful knowledge to measure heart rate during exercise to see how strenuous it is, and whether daily activities like walking can count as exercise.

Questions still exist whether these new technologies can improve health. Using certain smart devices can motivate you to change, but they will not do the work for you.

Shanthi Appelö is a registered and licensed dietitian nutritionist at the Knox County Health Department. She obtained her master's degree in public health nutrition from the University of Tennessee. She can be reached at [email protected]

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