30 Days with Fitbit (warning: long and geeky)
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segacs
Posts: 4,599 Member
Background
About me: Female, 5'1", 34 years old, SW 155, CW 128, GW 115.
Last month I got a Fitbit Flex as a freebie conference giveaway.
I'd been on here for about three months, steadily losing weight using the TDEE method. I wasn't logging or tracking exercise burns or eating back exercise calories, so I never really felt the need or desire to get an activity tracker because knowing how many steps I took each day was sort of moot.
But when I got the Fitbit for free, I said, hey, why not? More data! I like data. Data and I get along. I'd already been tracking my progress in an Excel spreadsheet I created myself, to chart daily weigh-ins against a trend, as well as a rolling average of actual observed TDEE based on calories consumed and weight loss on a 7-, 14-, 30-, 60- and 90-day basis.
I figured I could do a little experiment with the Fitbit. How accurate is it? Could it provide me with any useful data to help my weight loss efforts?
What I did
I decided to wear the Fitbit for 30 days and track results.
I set up the Fitbit, entered all my data, and put it on my wrist. I deliberately did not link it to MFP -- I wanted to measure the numbers against each other in parallel. In practice, that meant I had to log my daily weigh-ins in both MFP and Fitbit, which was kind of a pain, but I didn't want the data to sync and throw off my little experiment. I wore it all the time for 30 days, except for in the shower (I don't trust the water resistance claims) and when it was charging (which I tried to do while I was sitting anyway).
I continued to eat at my custom calorie goal I'd set for myself at MFP. I tracked food at MFP but not on Fitbit.
I also didn't track any non-step exercise on Fitbit, even though I did some minor strength training, kickboxing, some aerobics and calisthenics. But it was a good month for a test because I was in recovery from a calf strain injury and was forced to pare down my other exercise significantly while I completed physiotherapy to get it back to full strength. So most of my calorie-burning activity did in fact come from walking this month.
What I found
Over 30 days, here were the results that I got:
Analysis:
Step Tracking:
I think the Fitbit is fairly accurate as a step counter. The few times I tried to calibrate it by counting steps, it was almost perfectly dead on.
It did count a few "ghost" steps from time to time if, say, I was on a bumpy bus ride, or moving my wrist a lot, for example, trying on clothes. It also under-counted at times, like when I was pushing a grocery cart or carrying shopping bags. I wore it on my right wrist and set it to non-dominant (I'm left handed) and it didn't seem to count too many steps from things like typing. It may have under-counted some steps since I typically carry my purse on my right shoulder, and use my elbow to sort of keep it in place when I walk, so I don't swing my right arm as much. But it seemed to measure those steps okay.
The game-ification of the way the chart data is presented, and seeing the lights come on each time I got to another 2000 steps, were decent incentives to walk more. I found myself taking the stairs a lot more, taking the long way around, and I was more motivated to take the metro instead of driving or to get outside for lunchtime walks, even despite the bitter brutal cold weather we've been having. I think it's a decent way to get me more aware of walking and to encourage me to walk more.
It's quite expensive compared to a cheap pedometer, though, so I don't think it's necessarily worth it for step counting alone.
Calorie Tracking
Here I think the case is a bit harder to make. Fitbit is converting steps to calories using an algorithm, of course. It doesn't directly measure calories.
It's quite difficult to compare Fitbit to actual, since there's so much room for error and this is by no means a scientific experiment. My calorie counting could be off -- I try to be accurate, but I do eat out in restaurants fairly often, and even home-cooked food weighed on the scale has some margin for error. My non-step exercise, such as it was this month, would have burned some additional calories that Fitbit couldn't measure. Also, the 30-day period is arbitrary; weight loss isn't linear, and fluctuations on the scale mean that I could pick any time period and get a number that is higher or lower than what Fitbit said. In fact, that's why I compared the actual value to the trend value (according to the Libra Weight Manager app), and, as you can see above, Fitbit's estimate was lower than the actual but higher than what Libra says my adjusted TDEE would be based on trend.
On the whole, I think the calorie estimate isn't bad, especially for an activity tracker that doesn't measure heart rate. It was fairly close to the range I'd estimated for myself.
I don't think I'd find it particularly useful to sync it to MFP, though. The calories adjust so many times during the day that I think it would drive me crazy to try to meal plan against a constantly moving target.
I also think that, once I resume a more normal workout schedule, including more non-step cardio (like skiing, cycling, etc.) the accuracy would decrease. The activity tracking in both MFP and Fitbit is notoriously inaccurate, and the frustration of trying to wildly guesstimate exercise burns is one of the main reasons I switched to a TDEE average method in the first place.
The one useful thing I learned is that my NEAT is probably closer to lightly active or active. I'd set MFP to sedentary at first, since I have a desk job and sit on my butt all day. But it turns out I actually walk more than I thought I did in my daily life. But then, I'd already figured that out just by tracking actual observed TDEE -- when I'm doing my workouts, I'm finding it's closest to the middle activity setting (3-5hrs/week of moderate activity) on the Scooby calculator, once I take body fat % into account. Subtracting the gym workouts from that, I get lightly active, which is what I've now set MFP to say. In practice, since I'm using custom calorie goals anyway, the only difference that makes is in making those utterly useless 5-week weight loss predictions that you get when you close your diary slightly more accurate.
Sleep Tracking:
I did use the sleep tracker on MFP out of curiosity. On average, it takes me about 7 minutes to fall asleep, and I typically get about 7 hours of sleep -- a bit more on weekends, and the least on Sunday nights.
I honestly found this part to be a bit gimmicky, since it wasn't telling me anything I didn't already know. I suppose for someone with insomnia or specific sleep goals, it might be useful, but for me it was pretty much moot.
Conclusion:
It was a fun experiment but I don't think I'm going to keep using the Fitbit. It's sort of ugly and obvious on my wrist, gets in the way of my watch, and isn't exactly all that elegant looking. It was sort of fun to learn a few things about my normal activities, but ultimately it was all fairly moot in terms of my weight loss efforts.
But who knows? Maybe I'll dig it out again and give it another try if I hit a plateau. It did motivate me to walk more, so I think its biggest benefit was a sort of placebo effect.
About me: Female, 5'1", 34 years old, SW 155, CW 128, GW 115.
Last month I got a Fitbit Flex as a freebie conference giveaway.
I'd been on here for about three months, steadily losing weight using the TDEE method. I wasn't logging or tracking exercise burns or eating back exercise calories, so I never really felt the need or desire to get an activity tracker because knowing how many steps I took each day was sort of moot.
But when I got the Fitbit for free, I said, hey, why not? More data! I like data. Data and I get along. I'd already been tracking my progress in an Excel spreadsheet I created myself, to chart daily weigh-ins against a trend, as well as a rolling average of actual observed TDEE based on calories consumed and weight loss on a 7-, 14-, 30-, 60- and 90-day basis.
I figured I could do a little experiment with the Fitbit. How accurate is it? Could it provide me with any useful data to help my weight loss efforts?
What I did
I decided to wear the Fitbit for 30 days and track results.
I set up the Fitbit, entered all my data, and put it on my wrist. I deliberately did not link it to MFP -- I wanted to measure the numbers against each other in parallel. In practice, that meant I had to log my daily weigh-ins in both MFP and Fitbit, which was kind of a pain, but I didn't want the data to sync and throw off my little experiment. I wore it all the time for 30 days, except for in the shower (I don't trust the water resistance claims) and when it was charging (which I tried to do while I was sitting anyway).
I continued to eat at my custom calorie goal I'd set for myself at MFP. I tracked food at MFP but not on Fitbit.
I also didn't track any non-step exercise on Fitbit, even though I did some minor strength training, kickboxing, some aerobics and calisthenics. But it was a good month for a test because I was in recovery from a calf strain injury and was forced to pare down my other exercise significantly while I completed physiotherapy to get it back to full strength. So most of my calorie-burning activity did in fact come from walking this month.
What I found
Over 30 days, here were the results that I got:
- Average steps taken: 9421
- Average calories burned according to Fitbit: 1904
- Actual weight lost: 6.4lbs
- Actual observed TDEE: 2042
- Difference from Fitbit calories: -7.3%
- Trend weight lost: 4.5lbs
- Trend observed TDEE: 1820
- Difference from Fitbit calories: +4.4%
Analysis:
Step Tracking:
I think the Fitbit is fairly accurate as a step counter. The few times I tried to calibrate it by counting steps, it was almost perfectly dead on.
It did count a few "ghost" steps from time to time if, say, I was on a bumpy bus ride, or moving my wrist a lot, for example, trying on clothes. It also under-counted at times, like when I was pushing a grocery cart or carrying shopping bags. I wore it on my right wrist and set it to non-dominant (I'm left handed) and it didn't seem to count too many steps from things like typing. It may have under-counted some steps since I typically carry my purse on my right shoulder, and use my elbow to sort of keep it in place when I walk, so I don't swing my right arm as much. But it seemed to measure those steps okay.
The game-ification of the way the chart data is presented, and seeing the lights come on each time I got to another 2000 steps, were decent incentives to walk more. I found myself taking the stairs a lot more, taking the long way around, and I was more motivated to take the metro instead of driving or to get outside for lunchtime walks, even despite the bitter brutal cold weather we've been having. I think it's a decent way to get me more aware of walking and to encourage me to walk more.
It's quite expensive compared to a cheap pedometer, though, so I don't think it's necessarily worth it for step counting alone.
Calorie Tracking
Here I think the case is a bit harder to make. Fitbit is converting steps to calories using an algorithm, of course. It doesn't directly measure calories.
It's quite difficult to compare Fitbit to actual, since there's so much room for error and this is by no means a scientific experiment. My calorie counting could be off -- I try to be accurate, but I do eat out in restaurants fairly often, and even home-cooked food weighed on the scale has some margin for error. My non-step exercise, such as it was this month, would have burned some additional calories that Fitbit couldn't measure. Also, the 30-day period is arbitrary; weight loss isn't linear, and fluctuations on the scale mean that I could pick any time period and get a number that is higher or lower than what Fitbit said. In fact, that's why I compared the actual value to the trend value (according to the Libra Weight Manager app), and, as you can see above, Fitbit's estimate was lower than the actual but higher than what Libra says my adjusted TDEE would be based on trend.
On the whole, I think the calorie estimate isn't bad, especially for an activity tracker that doesn't measure heart rate. It was fairly close to the range I'd estimated for myself.
I don't think I'd find it particularly useful to sync it to MFP, though. The calories adjust so many times during the day that I think it would drive me crazy to try to meal plan against a constantly moving target.
I also think that, once I resume a more normal workout schedule, including more non-step cardio (like skiing, cycling, etc.) the accuracy would decrease. The activity tracking in both MFP and Fitbit is notoriously inaccurate, and the frustration of trying to wildly guesstimate exercise burns is one of the main reasons I switched to a TDEE average method in the first place.
The one useful thing I learned is that my NEAT is probably closer to lightly active or active. I'd set MFP to sedentary at first, since I have a desk job and sit on my butt all day. But it turns out I actually walk more than I thought I did in my daily life. But then, I'd already figured that out just by tracking actual observed TDEE -- when I'm doing my workouts, I'm finding it's closest to the middle activity setting (3-5hrs/week of moderate activity) on the Scooby calculator, once I take body fat % into account. Subtracting the gym workouts from that, I get lightly active, which is what I've now set MFP to say. In practice, since I'm using custom calorie goals anyway, the only difference that makes is in making those utterly useless 5-week weight loss predictions that you get when you close your diary slightly more accurate.
Sleep Tracking:
I did use the sleep tracker on MFP out of curiosity. On average, it takes me about 7 minutes to fall asleep, and I typically get about 7 hours of sleep -- a bit more on weekends, and the least on Sunday nights.
I honestly found this part to be a bit gimmicky, since it wasn't telling me anything I didn't already know. I suppose for someone with insomnia or specific sleep goals, it might be useful, but for me it was pretty much moot.
Conclusion:
It was a fun experiment but I don't think I'm going to keep using the Fitbit. It's sort of ugly and obvious on my wrist, gets in the way of my watch, and isn't exactly all that elegant looking. It was sort of fun to learn a few things about my normal activities, but ultimately it was all fairly moot in terms of my weight loss efforts.
But who knows? Maybe I'll dig it out again and give it another try if I hit a plateau. It did motivate me to walk more, so I think its biggest benefit was a sort of placebo effect.
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Replies
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For people who like to see things more visually:
The purple line is a rolling 30-day average of actual observed TDEE based on the calories I logged and the weight that the scale says I lost.
The blue line shows the calories Fitbit said I burned each day.0 -
Cool! I agree with you and I always wondered how accurate the calories burned was. I noticed when I was folding laundry I got a lot of "steps" but like you said pushing a shopping cart didn't register as many so I figured it kind of balanced out throughout the day. I do have mine synced to MFP and it's irritating. It gives me extra calories everyday and I don't feel it should. I noticed myself eating more because I had the extra calories and I wasn't losing weight. It did make me more aware of walking and I would walk around more so that was the biggest plus, but a cheap-o pedometer did that for me too.0
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You had me at long and geeky
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Very interesting. That is more accuracy than I would have expected.
I use a FitBit Zip (not synced to MFP) and I like it because you can wear it under clothes--makes it easy to keep it on even when you are dressed up. I get a lot of my steps from dancing, so I need something that I can wear with/under a dress. Because it is not on your wrist, you do not get phantom steps, and it tracks just fine if you happen to be walking while not moving your arms or hands. The Zip does not track sleep, but I have heard from many people that the sleep tracker on the higher-end models is not very accurate anyhow.
For me, the competitive aspect of the Fitbit site is extremely motivating. In the last week, I've done more than 100,000 steps--that's 50 miles!
I've always been pretty active, but this helps me to get in more casual activity in addition to intense workouts.0 -
Love it. Great stuff.0
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Great review! I love my Zip, since I get the benefits I need w/out the ugly bracelet (just need an MFP sync/step counter/TDEE estimator/gamification, and pretty reports in one place, since I'm too busy to do them myself ).
I've gathered data with it over the last 6 months, and I can say that the longer I use it, the closer the actual vs. trend vs. Fitbit TDEE estimates become. It still underestimates for me (YMMV), but I adjust my age to younger to make up the difference (younger = more calories). That is important for me as I move to maintenance, since I no longer want the "bonus" deficit.
All said, I think Fitbit has a good, solid product for us to gain a more refined/personalized TDEE number than online calculators can give (i.e. continual activity monitoring vs. just 4-5 "levels" of activity from which to choose).0 -
Very interesting, thank you0
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I enjoyed your research, thanks for sharing! Although i have to argue how could you not love your fitbit, oh well 0
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Love my fitbit ...moved from flex to zip just so it was less obvious and I could wear bracelets ...wouldn't be without it now0
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Thanks for sharing this. I'm using my fitbit more for maintenance but find it pretty accurate. I have the premium option and it tells me than since the start of January I should have lost 8.2lbs. My actual loss has been 6.4lbs. I think that's pretty good given that I am much looser with my logging now and I'm sure MFP is overestimating my calorie burn for swimming
My plan is to stay an average of 500cals a day below my goal cals and see how that pans out. So far so good. I average about 2700cals burned per day according to my fitbit and seem to still be losing 0.5 - 1lb per week eating an average of 2200 so that suggests it's pretty accurate to me?0 -
Thank you for the in depth post.0
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Nice to see all the replies! It's fun being surrounded by so many like-minded math geeks.
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I am late to the game, but thanks for this post. What a fun read!0
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Really great post, thanks for taking the time to share your findings with us in such a detailed way. Fascinating stuff.
I have the Zip and it's synced with MFP and I definitely agree with your observation that it's benefit is placebo effect largely. But hey it gets me moving, lol.0 -
What a great post! Beautifully geeky too. I have a charge hr linked to mfp and havek been struggling to accept the calories burned reading, on reflection I think I am more active than I give myself credit for. The one thing I have learned though; I REALLY love a graph!0
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Pretty much how I feel about a Flex! I did about six months of data analysis with the first Fitbits the year they came out, and my loss (35 lbs. or so) was right in line with what my Fitbit deficit predicted so for me it was pretty accurate.
But I too find the wrist models ungainly and refuse to wear them.
I also find I get annoyed with all the focus on steps after months of wearing them, too, so I do so for spurts but not for long. I prefer to focus on internal motivation to move more and there needs to be non-step activity in there (resistance). Data collection is a double-edged sword with me. It can be motivating but can get to feel like a nag, too.
Thanks for posting!
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Thanks for your post! I enjoyed it as well as the responses here.
The zip sounds like something I would be interested in.0 -
Great post and responses. Thanks for sharing. I have the Fitbit One and recently linked it to MFP. I use a TDEE range daily but find it useful to see the combined MFP/Fitbit data.0
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