Kind of Cool Fitbit thing

newyorkcitymom

This seemed like a good place to share this as I think it's a little too silly a thing to be excited about anywhere else. BUT...I got a fitbit charge hr a month ago and have been tracking my calories each day. So I just did the calculation of my avg daily burn vs avg daily intake to get my avg daily calorie deficit, which I then multiplied by 30 days and divided by 3,500 to get the amount of weight I should have lost if my logging and fitbit's stats were both accurate. It turns out, I should have lost 8.8 pounds in this time; I, in fact, lost 8.2. So I then took the difference, divided by 35 to get the calories this equals and then divided by 30 to find out how off my info was each day. It was exactly 70 calories - an insignificant amount.

Now, it turns out that I have not been logging my 1-2 espressos (made with a tablespoon or two of half and half and a tsp or two of sugar - neither measured) because it just didn't really seem worth it as I figured it was under 100 calories and is the only thing I don't bother with. But that's right about 70 calories. MEANING...my logging and my fitbit are both essentially 100% accurate. My logging is really pretty precise so it also means that I can feel very confident in my fitbit numbers.

This is exciting because it's really empowering because I feel like I have real data I can assess, trust and work with. Obviously, there are lots of other variables and it will not always work out this neatly, but it means I have tools that can help me to figure out a basic trend - hopefully downwards:)

Wanted to share because it was exciting, but also to share that I really do think you can count on fitbit (at least the HR one). And for the record, my calorie burns are pretty high - on a day where I feel like I do almost nothing, I'll burn 2,400 - 2,600 and on a day where I walk a lot (over 14,000 steps) or workout (couch to 5k or bike ride), I'll burn 2,600-3,300. My averages are 2,900 cals burned and 1,900 cals eaten. So I definitely do not feel deprived - I eat a desert most nights and have a beer or 2, 1-3 nights/week.

daniwilford

I got my Fitbit the first of July and have been using a spreadsheet to calculate pretty much as you have. In that time mine has been consistently over 90% accurate. As of today it is 98.79% accurate. That is good enough for me. It is one of the two best weight loss purchases I have ever made. The other is my digital food scale.

Kalikel

I haven't bought a jawbone or fitbit, but have used GPS apps to count my distance and estimate steps. The new iPhone does it for me now.

A friend of mine got an Apple watch last week and I was checking out the stuff he showed me. It's fun. I won't be buying one - I'll let my phone do it - but I get why people enjoy it.

I'm glad you enjoy yours.

lorrpb

Sounds great!! 100 cals per day = 10 pounds per year, and that's basically how I got from 150 to 300 pounds over the course of many years.

TahoeSki

NYC- thanks for sharing! I have a charge HR and love it; good to know how accurate it is!

ACSL3

I have a Fitbit One and I love it and have found it to be very accurate as well. Now I just need to log my food accurately...

suzeexoxo

I too have the Fitbit Charge and love it. But as well as the previous poster mentioned, I too need my logging to be more accurate.

Abby2205

Great news! I got a very similar result--like within 1% of theoretical. I actually wondered whether I had unconsciously biased my logging so that my calculated deficit would match actual weight lost, over a 14 week period. But that would be crazy, right? Or genius.

pandyg180

I just bought a charge this past weekend. I'm in love! It is great how I wake up each day with calories burned just from sleeping. I log my food on MFP and I synced it to fitbit. Also every step gets counted and I dont have to worry about having my phone on me all the time to track my steps on an app.

Bshmerlie

I have done the same thing with the data from my Fitbit charge HR as you did and my results were also spot on. As long as you log your food intake accurately you can can pretty much use it to make sure you maintain your 1000 calorie deficit each day. I average about 2500 burned per day which allows me to eat 1500 calories. But I have also noticed that as I have lost weight I now have to exercise more to get to that 2500 calories burned. It does get me off my couch because I like up the 2 pounds per week loss. It's a very useful tool.

segacs

I love the geekiness of this post! I can relate; I did pretty much the same thing with my Fitbit Flex and my spreadsheet data. Post is here:

http://community.myfitnesspal.com/en/discussion/10092120/30-days-with-fitbit-warning-long-and-geeky

Mine wasn't quite as accurate as yours. Over a 30-day period it was off by roughly 100 calories per day or so. But I also had to take into account how arbitrary the start and end dates were since the Fitbit is calculating instantaneous velocity (more or less) while the spreadsheet was calculating average velocity. In plain English, I could've started or ended my 30-day period on an unusually high or low weight day, which would throw off the data. So I also compared the Fitbit data to the trend weight for the same time period as logged by my Libra app, and I got a difference of roughly 100 calories... in the other direction.

Bottom line: It's never going to be 100% accurate. But it's a pretty decent guide.

BarbieAS

I've had a Fitbit for about 3.25 years. When you compare my logging to my Fitbit burns during that time, I "should" have lost approximately 167 pounds. I've actually lost 0.6. Now, obviously there's an issue with my logging as well (admittedly, I go through fits and spurts where I will weigh and measure EVERY morsel that enters my mouth for weeks and weeks, and then I get burnt out on that and go a little lax for a few days-weeks, rinse and repeat, though I'd say I've got pretty darn accurate logging about 80% of the time since May of 2012, and very generous estimates entered on the less-than-accurate days), but not to the tune of 500+ calories per day, every single day, for over 3 years - for me, personally, Fitbit's calculations MUST be significantly off as well. So, I'm sincerely very happy for you, and I mean absolutely no snark nor any disagreement with your results, but I just felt like I needed to mention the other side of the coin for other Fitbit users who read this post - YMMV, basically.

Alatariel75

This is really interesting! I have an HR and love it. I confess too that my logging isn't spot on so I can't run these kind of calculations - I'm a stickler during the week, but slack off on the weekend - that hasn't stopped me losing weight, just means I can't look at my data with your sort of accuracy!

newyorkcitymom

Does anyone know if there's a way to change your weight to your goal weight in fitbit for a day to see what your calories burned for the same activity would be at that weight? I find my fitbit tdee is pretty far above what most standard calculators assume it should be and so I would love to have a more accurate idea of what my calories would be at maintenance. I tried doing this yesterday by just switching the weight, but the cals burned didn't change. Is this something I would need to do at the beginning of the day? And if so would it throw off all my calculations or could I go back in and change it at the end of the day?

LivingtheLeanDream

Great post and totally agree! Fitbit is pretty accurate I've found but it does take logging really accurately to get results.

CyberTone

newyorkcitymom wrote: »

Does anyone know if there's a way to change your weight to your goal weight in fitbit for a day to see what your calories burned for the same activity would be at that weight?

Have you posted this question in the Fitbit Users group? I think you would get a lot of answers there.
http://community.myfitnesspal.com/en/group/1290-fitbit-users

BoxerBrawler

Great post! I love my Fitbit and never leave home without it! I haven't tracked with a spread sheet but I can say for sure that the calories consumed and burned synced with MFP is extremely accurate!

brightsideofpink

I did all the same math at one point. I too was off by about 75 calories every day and I was vexed. I was weighing everything. I later realized that fitbit has a way of extrapolating your exercise through to midnight. Whenever I'd have an evening class with a high step count late in the day, it would give me extra calories assuming I'd stay active. But I'd eat a late dinner and then crash. I finally started looking back the morning after a sync and realized it would change by about 50-60 calories the next day and I'd be in the red. I still eat back my exercise calories, but I always leave a 75 calorie buffer if I exercise after 6, lol.

IdLikeToLoseItLoseIt

Those are very exciting numbers and results, thank you for sharing!

KnitSewSpin

I'm one for which it's not accurate. I weigh and measure all of my food, I cook from scratch a lot so I manually enter all my recipes, etc. but I should have reached my goal weight a long time ago with the Fitbit numbers and I should be able to eat much more than I can to lose weight. I don't know what I'm doing wrong, but unfortunately the numbers just don't add up for me. It's very, very frustrating.

newyorkcitymom

Even if the Fitbit numbers are off for you, they still give you a baseline from which you can develop usable data. You can do the same exercise I did to determine the daily variance (eg, you seem to be burning 300 cals less than Fitbit says) and the you can create a food called Fitbit adjustment and enter those calories or enter a negative cal exercise for that amount. This adjustment should then give you a working number tailored to your actual experience.

I should also note that I have a charge HR, which I think is much more likely to be accurate.

Maxematics

Great post. I did the same and it says it's off by 122.5 calories, but I know weight loss isn't linear and the day after my weigh in I was a pound lighter and didn't log it. The Fitbit is very accurate though and I'm so glad I got it.

Also,

newyorkcitymom wrote: »

It turns out, I should have lost 8.8 pounds in this time; I, in fact, lost 8.2. So I then took the difference, divided by 35 to get the calories this equals and then divided by 30 to find out how off my info was each day. It was exactly 70 calories - an insignificant amount.

For those of you that were confused like me, she meant she multiplied the difference (.06) by 3500, then divided that by 30 to get 70.

The steps are (if you want to initially keep everything in absolute value):

• A=(30 Day Average Calorie Burn - 30 Day Average Calorie Intake)*30
• A/3500=B (The amount of weight you should have lost)
• B - Actual Weight Loss = C (difference)
• (C*3500)/30 = The "error" in calorie consumption.

chelleb1974

This is great to read! I bought a Fitbit a week ago and love it, and was wondering about the accuracy of the calories burned in a day. I thought of calculating it out (I love math, hah) and hadn't gotten around to it yet. I think I will give it a month and see if I lose and then re-assess. I do log as accurately as I can (probably 90% accurate), so if I stop/don't lose I will re-assess the fitbit numbers (and my logging). My first weigh in is tomorrow (didn't get on the scale when I first re-started MFP...waited a few days) so we'll see how it goes.

rune1990

I was off by approx 93 cals per day (and that is totally attributed to my logging) which works out to .8 lbs over 28 days!


I love my charge HR. I can't wait to calculate this at a years time.

CazzieH123

I have the fitbit surge. And I love it. Best thing I ever bought! It's 100% accurate. And that works for me

winddancinash

I just bought the Charge HR two days ago, and I ADORE it! Love being able to see the calories I'm burning just from moving around and doing everyday things.
I'm still trying to figure some stuff out with it though. Does it take anyone awhile for it to sync to MFP?

nyponbell

This is fantastic! I can't wait until I've gone a month of proper logging (again) to do something similar. As it is, I'm now just writing down my stats for the week and how much I should've been losing; to see if I'm getting there.

Of course, I also have to be consistent in weighing myself...

But this makes me very happy. I also have an HR and sometimes it feels like the burn is quite high; but then I also have days when I walk close to 30k steps.

newyorkcitymom

Also, ifyou can mentally handle it, I find weighing every day helpful. It may seem obsessive but actually it helps me NOT obsess over any individual day's weight but to see the averages week over week and the overall trend. I sync to trend weight, which also helps to focus on the trend.

segacs

newyorkcitymom wrote: »

Also, ifyou can mentally handle it, I find weighing every day helpful. It may seem obsessive but actually it helps me NOT obsess over any individual day's weight but to see the averages week over week and the overall trend. I sync to trend weight, which also helps to focus on the trend.

Ditto.

cebreisch

Knowledge is power!!! I've always loved the data I get from syncing MFP with Fitbit. It really helps me see where I am with calories in vs calories out and that the bigger the difference, the better the scale is each week. Don't get me wrong - I don't ever starve myself (food addict big time!) but it just gives me some comfort in being able to see the data and get positive results - that the scale decreases.