There are many reasons I’m not a fan of tracking calories as part of changing your relationship with food and becoming more healthy — one of the biggest is that it’s hard to be accurate. And when you make important decisions based on bad information, it’s easy to get yourself in trouble.
For example, in your prior weight loss efforts you might have relied on tracking every calorie you ate during the day. And if you went out to eat you relied upon the calorie counts on the menu (if the restaurant gave them) in deciding what to order. The bad news is that the published calorie numbers are rarely 100% accurate, and there’s a good chance that the meal you ate might have contained at least 50-100 calories more or less than you though.
But the uncertainty isn’t just an issue with the “input” part of the outdated “calories in, calories out” equation. It can also be quite difficult to measure the amount of calories you burn through exercise or extra activity. And surprisingly, it’s difficult to measure calorie burn even if you use an activity tracker or fitness app on your smartphone.
Among the more popular devices are things like Garmin’s Vivofit and Vivosport lines, TomTom lifestyle and fitness devices, various trackers by Fitbit and Moov, smartwatches and trackers by Samsung, and the Apple Watch. You might use one of these already. And they can be a powerful tool in finding motivation, community support, and tracking your progress.
But they’re not so great at measuring calorie burn.
A recent study by researchers at Stanford University found that all the tracking devices they tested gave inaccurate date with respect to energy expenditure (http://www.mdpi.com/2075-4426/7/2/3/htm). The error rates were surprisingly high; ranging from 27.4% to 92.6%! And if you spend a few minutes browsing the support forums of some of these devices, you’ll find a lot of people who are finding that the devices tend to err on the side of overestimating your calorie burn.
Think about that for a minute, if you’re still sticking to the notion of counting calories being the foundation of improving your health and fitness (don’t do it!), and you’re basing your meal choices in part on how active you are, your device may be throwing your calculations off by giving you “permission” to eat more.
The companies are working to make their devices more accurate, but there’s always going to be some element of unreliability in the numbers they give. Your body is a complicated and dynamic organism, and there are much more effective ways to approach healthy eating.
Use your fitness tracker if it helps you stay motivated or connected to other people looking to improve their health, but don’t let it drive something as important as the food you eat. Making smart food choices and eating primally with an emphasis on vegetables is a better path to weight loss and health.