I used to be an avid user of fitness trackers.
If I was going for a run, I'd use the RunKeeper app to track my miles and pace. If I wanted to know how many calories I was "allowed" to eat, I used MyFitnessPal. Then, Fitbit was invented so I could track all of that data with even more accuracy all in one place.
To be clear, I still wear my Fitbit and use it frequently. But to be honest, I don't recommend that everyone use it - especially if you are not at peace with your body in relationship to food and exercise.
The Benefits of Fitness Trackers
Apps and devices that track food and exercise can be helpful if you have specific goals in mind that have been given the OK from your doctor. If your doctor has recommended you try a specific diet, the MyFitnessPal app is perfect for tracking that. The app has a library full of thousands of foods and even a barcode scanner that makes inputting the foods you eat simple. If you need to track calories for a weight loss or gain goal, it's important to actually keep track of that data on the app rather than estimating in your head. And if you're specifically trying to stay within certain macronutrient parameters (fat, carbohydrates, and protein), you can adjust these levels in the app, which will then determine your "allowance" for each group for the day.
Fitbit and other exercise trackers can be a great way to track your activity for the day. These trackers can give a pretty accurate reading by using heart rate monitoring and GPS to track movement and distance. Again, if your doctor has recommended a certain amount of exercise per day or a calorie goal, using a wearable fitness tracker can be a helpful tool.
The Drawbacks of Fitness Trackers
Like I mentioned earlier, I still use my Fitbit frequently and enjoy learning from the data it provides. However, there was a time in my fitness and nutrition journey when using a fitness tracker would have been detrimental to my health. When I first started working out frequently and noticing some body changes, tracking my calories consumed and burned became an obsession. I reported every morsel that I ate even before I ate it, just to see what I could still eat. I had no professional advice and set arbitrary weight loss and calorie goals. At one point, my calorie goal set on MyFitnessPal was just 1000 calories a day, and I'd praise myself if I went under that goal.
An app or device doesn't know you and your needs as well as a professional adviser. So a data tracker might be able to tell you information about your diet and exercise, but it can't tell you whether or not those choices are actually healthy for you.
I've grown a lot since that time when calories ruled my life, and since I don't have any major health concerns that my doctor wants me to watch, I don't track the calories I eat or burn. I no longer log these things and I eat intuitively, based on what my body tells me I need and the environment I'm in. I know that if I started tracking again, I might find myself in a similar, obsessive state that I want to avoid.
The Bottom Line
For most people, fitness trackers probably are not necessary, and they might not be a healthy resource for others with obsessive tendencies. I believe that if you want to live a healthy lifestyle, you should eat foods that make you feel good and exercise in ways that are fun and make you feel energized, not miserable. You don't need to run on a treadmill for an hour, slaving away just to burn calories. Find something that makes you happy, and explore it!
For others like professional athletes and people who have real health concerns, fitness trackers might be helpful to achieve the goals set by their trainers and doctors. And others might not have obsessive tendencies over tracking their data. My husband is a perfect example - he is simply curious about what he eats and only uses fitness trackers when he's training for something specific, like an upcoming race. In this case, I think trackers are a helpful tool.
The bottom line: know yourself. Know your tendencies, challenges and weaknesses. Fitness trackers can be a healthy resource for you if you can use them responsibly. But for people who struggle with obsessive tendencies when it comes to health, it might be best not to use these trackers for the sake of your mental health.