Is Fitbit One over-estimating my calories burned?

[elderwanda]

I have been meticulously weighing and logging all of my food intake since June, 2016.  In the very beginning, I was on the 1000 calorie deficit, and lost 2 pounds every week.  But since I'm only able to eat about 1000 calories on that deficit, I couldn't stay with that for more than a month or so, so I went to the 750 calorie deficit.  

On on the 750 calorie deficit, I lost an average of one pound per week (Not 1.5).   After several months of that, I realized that I was starting to flag on only 1250 calories a day, so I bumped it up to a 500 calorie deficit.   Now, I'm exercising all the time in order to burn 2100 calories per day, and eating 1600.    I'm also doing Stronglifts 5x5 three days a week, in order to keep muscle loss to a minimum, and making an effort to eat about 120-130 grams of protein a day.  

Anyway, my concern is this.  Since going to the 500 calorie deficit, I have lost a grand total of about two pounds in the past two months.  (Or something like that.  It's been a few days since I looked at that data.)  I have lost 1.5 pound of fat and gained half a pound of lean body mass.  Realistically, the amount of muscle I may have gained will have been negligible, because I'm a middle aged woman in a calorie deficit, so I'm sure I haven't actually lost a pound of fat per week and replaced it with rock hard muscle.  I wish! 

So clearly something is up.  At a 500 calorie deficit, I should be losing a pound per week, on average.  I'm not.  I'm being meticulous about my food logging, so I doubt if that's been consistently wrong.  I wear a Fitbit One and it calculates my calories based on my steps and the current info that it has from my Aria scale.  (143 pounds, 33% BF, 95 pounds of lean body mass)   I do not log in any extra exercise, like my Stronglifts workouts, because the majority of that time is spent resting between sets, and my lifts are challenging for me, but probably not heavy enough to burn significant calories.  But to be on the safe side, I don't even attempt to log that as calories burned.  

So... Could it be that my Fitbit is over-estimating the calories I burn?  That doesn't seem right either.  According to a chart I found, a person of my weight burns 84 calories when walking one mile, and that's exactly what my Fitbit says for me, so that seems right.   When I sleep, apparently I burn 4 calories every five minutes.  Could it actually be less than that?  

I'm in this for the log haul, and if it takes me ten years to get to get to 125 pounds and 22% BF, then so be it.  But frankly, I can feel that menopause is fast approaching, and I'm afraid that all of this is going to become much harder.  I want to lose as much fat and build as much muscle as I can before then.  

Every so often I attempt to bump the deficit up a bit for a day, but I just am not able to eat less than about 1600 calories in a day without being miserable.  I can do it, but then I lie in bed with my stomach going, "feed me!", and have to go eat a yogurt or something in order to sleep.  And I don't have the physical energy or time to exercise enough to burn over 2100 calories on most days.  So how do I get a calorie deficit that will allow me to be "not obese" sometime before the year 2050?   Any thoughts would be appreciated. 🙂    

Oh, also, when thyroid levels were checked last year, they were fine.  

[UVcat · Accepted solution]

I wonder if you might benefit from a diet break.

Now, I'm not going to say your body is in "starvation mode"; I don't really believe in that in the way it is usually brought up, but adaptive thermogenesis is a real effect and could conceivably be responsible for your burning some few hundred fewer calories than your One predicts.

FWIW: I had a flex when I was logging calories and losing 0.5 lb/week for a 250 cal deficit, as predicted, but also hit some sort of wall after 6 months (this was three years ago). At the time, I ended up deciding I had stopped being 100% accurate and honest with my food logging, but it could well be that I needed a diet break, instead or in addition. My impression from these boards was that the One actually tended to underestimate calories burned relative to the wrist-worn models.

Also, I would definitely take the BF% readings from your scale with a large grain of salt. I think the accuracy of that method is +/-5%, and maybe worse for women (we have more water-retention fluctuations on average and may also have a fat distribution at odds with the model the scale uses). 

Hope that helps! And: Congrats on your progress so far!

-UVcat

[AuroraKat]

You mentioned that you are exercising "all the time" and also doing a strength-training program. What is your exercise routine? Also, what is your height and age (if you are comfortable sharing)? And, you are still weighing your food, not just estimating portion sizes?

Without knowing more details, my first guess is that you are overtraining and/or not eating enough. You may have also become more efficient with your fitness routine. This is where cross-training becomes important. If you've been walking for exercise, why not try swimming, biking (stationary or otherwise), etc. to target different muscles? Also, you can look into HIIT routines, which are very effective for fat burn. Finally, make sure you are scheduling rest days - they are just as important as all the other activities that you engage in. 

[elderwanda]

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Thank you!  I think I will go ahead and try bumping my calories up to 2000, which is supposedly my maintenance level-- although if I have a couch-potato day, then my end-of-day calories burned is more like 1700, so I guess "maintenance" means, "maintenance as long as you're getting your 10,000 steps. 

Anyway, it can't hurt to give it a try, and it sort of makes sense.  I'll eat 2000 calories a day for the next 14 days and then go back to the 500 calorie deficit and see what happens.  Worst that can happens is I'll gain a couple of pounds and have to re-earn my "30 Pounds Lost" badge, right? 🙂

I'm pretty sure the bodyfat readings are reasonably accurate, or at least it's been consistently going down slowly.  It was 41% when I started, at 173 pounds.  I don't have a lot of fluctuations or anything that seems to coincide with monthly "events".  I'll occasionally have a sudden jump up or down of as much as a pound, but no more than that.  Usually fluctuations are more like half a pound.  Just poking around at my body, I can believe that a third of it is fat.  All in my belly, too.  Whee!  

[elderwanda]

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@AuroraKat wrote:

You mentioned that you are exercising "all the time" and also doing a strength-training program. What is your exercise routine? Also, what is your height and age (if you are comfortable sharing)? And, you are still weighing your food, not just estimating portion sizes?

Without knowing more details, my first guess is that you are overtraining and/or not eating enough. You may have also become more efficient with your fitness routine. This is where cross-training becomes important. If you've been walking for exercise, why not try swimming, biking (stationary or otherwise), etc. to target different muscles? Also, you can look into HIIT routines, which are very effective for fat burn. Finally, make sure you are scheduling rest days - they are just as important as all the other activities that you engage in. 

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I'm 49 years old, and 5' 3".  I'm still weighing my portions.  There are occasional exceptions, like if my husband cooks dinner and says, "I used about a tablespoon or two of butter"...so I have to guess what's actually in my portion--- but that only happens once or twice a month.  Mostly everything I eat is in my control.  

 My exercise is just walking whenever possible, and a bit of jogging in place several times throughout the day.  I typically have two or three fifteen minute intervals of "high intensity" exercise during a day, and a bunch of "moderate intensity".   It feels like a lot time-wise, but I don't feel like I'm wearing myself out with too much exercise or anything.  In fact, I have more energy nowadays that I did when I used to sit on my butt all day. 

When I started out, back in June, slow walking was all I could do--- partly because of just being so out of shape, but also because I was just too heavy to move my body very quickly without feeling like my feet were being crushed under my own weight.  I realize that sounds kind of silly, since I was only 173 pounds max, which is a comfortable weight for plenty of people, but my body never seemed to adapt very well to carrying extra weight.   Years ago, pre-pregnancies, I could always tell when my weight snuck up to a whopping 130 pounds because my feet would start to ache, and I would feel uncomfortably heavy.  Sounds weird, I know.  

Anyway, I basically just do what I can to get 12,000 steps a day, which is what it takes to get my calorie output high enough that I can eat a reasonable amount.  I'll walk as much as I can, and then spend some time jogging in place (now that I'm fit and light enough to do that) in order to get any extra steps I need.  The fitter I get, the more stuff I can do, but I'm starting at a pretty low point.  In hindsight, I realize that I probably lost a lot of muscle mass in my teens and 20's from chronically undereating (some poor diet choices, but also some stuff out of my control, like Air Force basic training where I lost 10 pounds I didn't have because they only gave us about two minutes to eat each meal, and being poor for a while), and then I gained a bunch of fat from being sedentary and too depressed and out of touch with my body to realize what was happening.  Good times, eh?  But those days are gone and I'm getting better.  Yay!  

@I suspect that @UVcat may be on to something with her suggestion that I've been in a calorie deficit for too long, so I'm going to give eating at maintenance a try for a couple of weeks.  But putting some variety in my exercise routine is probably a good idea too.  I admit, one problem with swimming or biking (other than not having access to a pool or a bike) is that my Fitbit won't count either of those, and I like being able to see the steps and calories go up! 

As far as rest days are concerned, I've always been sort of afraid to take them.  On the rare occasion that I do, I get to the end of the day and see that my Fitbit says I've burned like 1600 calories for the entire day.  Psychologically, that's difficult to take.  And also I just feel kind of restless and dissatisfied when I'm sedentary these days.  

[UVcat]

I hope it helps; and that you'll report back, you definitely seem to have the right attitude! 

That totally makes sense about the BF scale; sounds like you're watching the trends, not getting overly hung-up on particular numbers.

And: I missed some math in your first post: you've lost 30 pounds already, that's awesome!! 

-UVc

[elderwanda]

Update: Well, it's been a week since I started my "diet break".  I'm still counting calories but instead of setting up my Fitbit app so that I'm on a 500 calorie deficit, I've set it for about 2000 calorie per day, and trying to make sure that my calories in and calories out come out about even at the end of the day, so between about 1950 and 2100.  I've also cut down my steps goal from 12,000 to 10,000.

For the most part, eating at maintenance still feels like just a bit less that I would naturally eat if I weren't logging it all, which explains how I gained weight in the first place.  Also I wasn't making an effort to exercise back then, so realistically was probably burning no more than 1600 or 1700 in a day, and probably eating more like 2300 or 2400.  It looks like not getting heavy again is going to be a lifetime commitment.  

I haven't weighed myself, but I don't feel like I've gained any weight this week. Since I'm not in a calorie deficit, I've been using the opportunity to increase my strength training a bit.  Got my deadlift up to a whopping 100 pounds, which is more than my lean body mass, so go me! Ha ha!  (I started out being told that everyone on the planet can start with 135 pounds at least.  That is not true.)  

Anyway, I'll be staying at maintenance calories (2000-ish) for another week, and then bump it back down to a 500 calorie deficit as before (probably through a combination of more exercise and less food).  We'll see if that bumps my metabolism into gear.  🙂

[richendaherzig]

I visited today to find out how accurate the calorie consumption estimates of Fitbits tend to be. Only one post in this thread has commented on that question directly. I'd be interested in hearing more if anybody has any relevant knowledge or experience? I'd like to know whether I can use my Fitbit's estimation of calories burned and used (I use it in conjunction with My Fitness Pal) as a basis for eating targets every day.

"I do not log in any extra exercise, like my Stronglifts workouts, because the majority of that time is spent resting between sets, and my lifts are challenging for me, but probably not heavy enough to burn significant calories."

IMO you should log this exercise. It does a lot more than you might intuitively think. Keep up the good work!

I wanted to second one of the other posters who mentioned that you might just have become too adapted to your current exercise level. Try to keep on levelling up and not staying on the same intensity or resistance weight for too long. I also found high intensity training amazing for weight loss. I didn't really look into the official guidelines for HIIT but I used the same concept. I'd do 2 minutes of pushing myself as hard as I could physically manage and then 4 minutes of more relaxed cardio, and repeat. I'd do that for 30 mins (exercise bike, but same applies for running, elliptical, etc) most days. It was not fun but boy did it work >.<

Finally I hear from a lot of people that they experience plateaus in weight loss. I think there are a number of factors behind this, and that it doesn't necessarily mean that what you're doing is not working. Keep going, and well done! 

[UVcat]

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@elderwanda wrote:

Update: Well, it's been a week since I started my "diet break".  I'm still counting calories but instead of setting up my Fitbit app so that I'm on a 500 calorie deficit, I've set it for about 2000 calorie per day, and trying to make sure that my calories in and calories out come out about even at the end of the day, so between about 1950 and 2100.  I've also cut down my steps goal from 12,000 to 10,000.

For the most part, eating at maintenance still feels like just a bit less that I would naturally eat if I weren't logging it all, which explains how I gained weight in the first place.  Also I wasn't making an effort to exercise back then, so realistically was probably burning no more than 1600 or 1700 in a day, and probably eating more like 2300 or 2400.  It looks like not getting heavy again is going to be a lifetime commitment.  

I haven't weighed myself, but I don't feel like I've gained any weight this week. Since I'm not in a calorie deficit, I've been using the opportunity to increase my strength training a bit.  Got my deadlift up to a whopping 100 pounds, which is more than my lean body mass, so go me! Ha ha!  (I started out being told that everyone on the planet can start with 135 pounds at least.  That is not true.)  

Anyway, I'll be staying at maintenance calories (2000-ish) for another week, and then bump it back down to a 500 calorie deficit as before (probably through a combination of more exercise and less food).  We'll see if that bumps my metabolism into gear.  🙂

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Thanks for the update! I think it makes some sense to stay away from the scale since in a two-week period it would be difficult to separate the water weight re-bound from going to (or close to) maintenance from any possible actual gradual increase from your maintenance calories perhaps being over-estimated.

In any case, after a week or two of being back on a deficit, I would be really curious if you could "back out" whether you lost/maintained/gained during the two week period where you trusted Fitbit's maintenance calories. Good experiment!

And, that's awsome about your lifts! Enjoy yourself!

Best,

UVc

[Dominique]

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@richendaherzig wrote:

I visited today to find out how accurate the calorie consumption estimates of Fitbits tend to be. Only one post in this thread has commented on that question directly. I'd be interested in hearing more if anybody has any relevant knowledge or experience? I'd like to know whether I can use my Fitbit's estimation of calories burned and used (I use it in conjunction with My Fitness Pal) as a basis for eating targets every day. 

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Several people (for instance, @A_Lurker and @GershonSurge) who have been logging their intake very meticulously have posted on that in the past. Since everyone is unique and we often use different trackers, I think each of us needs to find out what applies to them. Just because someone else found his Surge overestimated energy expenditure by 10% doesn’t mean the same will apply to you and your Blaze.  

[GershonSurge]

Most people aren't great at math. In my opinion, the easiest way to determine how much to eat is start with a 1,000 calorie deficit for a device with a heart rate monitor and a 500 calorie deficit for the clipons. The calories consumed shouldn't be lower than the Basal Metabolic Rate (BMR). Then adjust from there based on weight loss over at least 30 days or hunger pangs (not cravings.)

One person who used to come here ate his BMR every day and exercised a lot. It worked well for him.