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30 Days of Crossfit with a FitBit Flex: My Review

I’d been thinking about buying an activity tracker and had it narrowed down to a couple with the Fitbit Flex leading the charge. My wife mentioned wanting one so I stopped by WalMart one random Tuesday night on the way home and bought one for each of us.

Fitbit measures a handful of things, all based off of your movement. I have my primary goal set track my steps while my wife selected calories. It still monitors everything, but when you hit your goal it vibrates to let you know.

Crossfit and the Fitbit

I wanted a Fitbit so that I could see how far I walk every day and how many calories I am burning. Of course, the natural extension of that is to see how many calories I burn during my workouts.

Very Active Minutes

Fitbit tracks what it calls “very active minutes”. I expected this to go nuts during a Crossfit workout. Surely coming that close to death would translate into a wheelbarrow full of very active minutes. Turns out almost losing consciousness several times during a workout is good for about 3 very active minutes. One workout included a lot of running, so I managed 7 active minutes! All I could think was, “I don’t know how to Crossfit!”


On the flip side, when I am doing yard work or house work, it usually records around 30 very active minutes. Here is a capture from yesterday where all I did was push the lawnmower over the front and back yard. This does not include use of the weed eater or leaf blower.

According to my Fitbit, substituting an hour of Crossfit for an hour of yard work per day would give me a chance of stealing Rich Froning’s title as Fittest Man on Earth. Essentially the very active minutes are good for a laugh, but nothing more. And it turns out they don’t matter.

You may also enjoy 5 Things Your Won’t Find in a Crossfit Box

Calorie Tracking

As inaccurate as the active minutes appears to be, the calorie tracker seems inversely accurate. You can sit still and watch it change, but get moving and it counts faster. Even sitting still, you are burning calories. Fitbit accounts for this. (Order your’s here.)

Your resting metabolic rate is the number of calories your body burns in a day to keep you alive with no activity. When I had my body fat checked a few weeks ago, my RMR was 2,161 calories. That is what I should burn by laying on the couch all day. Fitbit set my goal for the day at 3,232 calories.

I glance at the calories in the Fitbit app (iOS and Android), but I pay more attention to MyFitness Pal. I use MyFitnessPal to track all of my food so I can make sure my macros (proteins, fats, and carbs) are where they need to be for the day. I also try to stay around 1,800 calories since I’m in the fat loss phase of my transformation.

Before Fitbit, I would log a Crossfit workout as 30 minutes of cardio. It was much simpler than trying to figure out how long I did each exercise. A workout is 60 minutes, but I’m not going all out for the full 60, so 30 seemed good. Now I use the FitBit to track this and it seems to do really well. The two apps are synced so MyFitessPal automatically imports data from Fitbit.


30 minutes of circuit training translated as 401 calories in MyFitnessPal. After my last Crossfit workout, the Fitbit logged an adjustment in MyFitnessPal of 370 calories. That seems right.

Other Things Fitbit Does Well

With the exception of very active minutes, the Fibit monitors several things quite well. We’ve already covered calories, so let me run you through a few other things you can get out of your Fitbit.


Step Count

The goal is 10,000 steps per day. Some days I spend a majority of my day at my desk, with occasional trips to the building next door. I was really curious to see how far I walked in a day. Now I know. So how does this help?

Here is the interesting thing about wearing an activity tracker. It can actually increase your activity! I used to let work collect on my desk so I only needed to make one trip next door. Now I might make 4 or 5 trips just to get in the extra steps to meet that goal.

Distance Walked

How far do you walk in a day? I was also curious to know this number. I was a little surprised to find that I typically walk 3.5 miles at work every day going from building to building. Wow. We’re also in the process of adding a jogging track on the land behind the building so I may start adding some running in at lunch to get those numbers up higher.

Like I mentioned earlier, the biggest surprise is yard work. One Saturday I never left the house. I did all of the yard work and cleaned house. I don’t have a large piece of land, but I still walked 5.24 miles! That is nuts.


Seeing how far you walk can motivate you to get moving. Maybe it’s parking farther out, or walking around your office more, but there is something about knowing your numbers and trying to beat them.

Sleep Tracking

Fitbit also does a great job tracking your sleep patterns. You activate sleep mode by tapping repeatedly until two lights flash in an alternating pattern. The hardest part is remembering to put it in sleep mode when you go to bed, and take it out of sleep mode when you get up.

After syncing to your phone, you can view a chart that shows how long you slept, how many times and minutes you were awake and how many times you were restless. The total time you slept doesn’t include minutes you were restless or awake. So if you were in bed 8 hours and you were restless for 30 minutes, it would only log 7 hours and 30 minutes of sleep.


Once you can see your sleep pattern, it is possible to look back and see if there was something that may have been affecting your rest. With some deductive work you may be able to tell if eating too many carbs or sugar made you restless, or if a day of heavy exercise helped you sleep better.

Overall Thoughts

Fitbit Flex is great for tracking steps, distance, sleep, and calories burned. Use MyFitnessPal for diet tracking and let it bring in exercise data from Fitbit. These two make a great pair. If you ignore the active minutes you should have a clear picture of how much movement you get in a day, including running or Crossfit workouts. Seeing the numbers can also motivate you to move more, and that seems to be the real benefit behind activity trackers.

Do you have any idea how many steps you take in a day or how far you walk?

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