The Truth about Fitness Smart Watches ( Apple Watch, Fitbit)

As a trainer, there are so many gadgets, supplements, and fads that irritate the hell out of me. While most supplements simply don’t do what they claim, other fitness fads can literally sabotage your goals due to the wrong information that they provide. Smartwatch brands such as Fitbit and Apple Watch continue to be one of the biggest trends in the fitness industry. These devices claim to provide the user with precise fitness information based on their workout and lifestyle, including daily steps, current heart rate, and calories burned. While steps and heart rate are important factors when measuring fitness, I’m far more interested in how accurate these devices are in measuring energy expenditure (calories burned).

While there are many variables that go into losing weight, there is only one true formula: total energy expenditure vs total caloric intake (calories out vs calories in). Being over your daily intake by as little as 200 calories (or about 1 serving of peanuts) not only sabotages your weight loss but also adds more inches to your waistline. In as little as eight days, over consuming just 200 calories will add roughly ½ lb. of body fat. With great importance comes great responsibility for these companies who claim that they provide accurate calorie readings. Current data shows that there are 29.5 million Fitbit users and an estimated 55 million Apple Watch consumers. Between the two companies, that’s a near 85 million people who rely on the analysis of the smartwatches to help them make lifestyle decisions based on what they believe to be precise information. But in reality, how accurate are they? Could they be making you fatter?

A study conducted by Stanford University took 60 college students and plugged them into a smartwatch from one of seven different companies. The two most popular companies are Apple and Fitbit; I wanted to take a deeper look into these two companies specifically. The study measured heart rate, steps, and calories burned. While the heart rate and steps were fairly accurate, with a margin of error at about 5%, energy expenditure (Calories) showed to be nowhere near precise. The study found that Fitbits’ accuracy was off by 27% and Apple’s calorie readings were off by an average of 40% in subjects. These numbers are enormous and will without question sabotage the user’s “weight loss” goals. Think about it this way, you complete a workout in the gym and look down at your smartwatch. You see 700 calories burned. You think to yourself “wow I crushed it today” and then proceed to eat an extra 300 calories thinking it fits your caloric budget. You have now gone 300 calories over your daily calorie budget. The 700 calories you thought you burned turned out to be 420. Going over 300 calories may not seem like a lot; however, when you want to lose weight, consistently consuming a surplus of calories to any degree leads to weight gain.

Why are they so inaccurate? Even the top experts agree that the margin for error is way too high and should be much more precise. While there is no clear-cut answer to this, I have a few ideas myself, some a little out there and some highly probable. Accurately measuring your energy expenditure is damn near impossible because there are so many different variables that are thrown into the mix: metabolism, body fat percentage, lean muscle tissue, weight, height, age and sex. These watches spit out your calories burned based on a few of these, like height, age, weight, and sex. I completely understand a margin of error and by no means expect them to be 95% accurate, but, as I said earlier, even the top experts think they should be much more accurate than 40% or even 27%.

Call me crazy, but maybe this is a marketing tactic to the consumer? While I understand that they have already purchased the product at this point, showing higher numbers when it comes to how many calories burned leaves the user satisfied, causing them to use this function at a much higher rate. If the user enjoys yet another app/function on the smartwatch, they are more inclined to purchase the product again. I know that may seem ridiculous, but why wouldn’t they up the numbers a bit to satisfy the consumer when they can’t be 100% accurate?

Many clients that I have trained, and currently train, love their Apple Watch. They get their hit of dopamine when they look at how good they did after a workout. If you are one of those people, I’m not suggesting that you throw away your smartwatch, especially because some of the other features are valuable. If the watch gets you off your ass and into the gym, then it's doing its job. What I am suggesting is that you veer away from looking at how many calories you’ve burned, or at the very least don’t pay attention to them. Instead of plugging the calories you burned from exercise into how many calories you should eat to lose weight, stick to a certain number of calories you need to eat each day for weight loss and consider the calories you burn from exercise a boost to get you to your goal that much faster.

Citation

https://med.stanford.edu/news/all-news/2017/05/fitness-trackers-accurately-measure-heart-rate-but-not-calories-burned.html#:~:text=and%20maternal%20health-,Fitness%20trackers%20accurately%20measure%20heart%20rate%20but%20not%20calories%20burned,heart%20rate%20within%205%20percent.&text=But%20if%20it's%20measuring%20energy,off%20by%20a%20significant%20amount.