What am I really burning? Fitbit +/vs Treadmill

[Solannis]

I am hoping someone out there can help me answer this question. The basic question is: which is more likely an accurate account of calorie burned when spending an hour on a treadmill: My Fitbit Surge or the treadmill's recount of calories burned at the end of my "session?"

Here is the background:

I am using a Lifestyle treadmill found in my company's gym. This is a gym/professional model, not a home unit. Has the TV up top and the full LCD display that lets me browse the web, review my workout stats, etc.

I do a standard workout on the treadmill: 60 minutes at a set speed (these days, 3.6 mph) with 0% incline, then a 5 minute "cooldown" where the treadmill drops my speed by 0.5 mph each minute for the 5 minutes (ending speed: 1.1 mph). At the start of this same workout, just before I step on the treadmill, I select and start an "exercise" on my Fitbit surge that does not use GPS and only collects heart rate information. When the treadmill stops, I stop the exercise on my Fitbit as well.

I do not enter my weight/height into the treadmill, but I did put that information into my Fitbit (via the website and the app). I do not hold the handles of the treadmill to monitor my heart rate at any point (in fact, I don't touch the treadmill at all with my hands, only my feet).

At the end of the workout, the treadmill tells me I burned 324 calories. My fitbit, however, tells me that I burned about 1,200 calories (varies a bit from workout to workout). That's quite a delta. Which one should I be using to account for my actual calories burned? The treadmill doesn't know my weight or height or stride, the fitbit doesn't know my speed or my stride; clearly they are both missing data, so how much can I trust their calculations?

Here's (what I think is) a bonus question: Since the Fitbit doesn't know how fast I am moving (2.5 vs 3.6 or any other speed), and it doesn't know my incline (which, at present I don't have/use one, but I could in the near future), how accurate (or even moderately close) is the Fitbit likely to be (just in general) when I use the treadmill? Or an elliptical? Or a stair climber? I don't care about or expect step-for-step accuracy, but based on the delta I am already seeing as described above, how close is the Fitbit to "truth?"

[dbanderson1]

@Solannis In order to compare you should enter you height and weight into the treadmill otherwise it will assume you are average (which you may or may not be).  Also exercise probably isn't the best mode because it will simply apply a generic physical activity coefficient to your basal metabolic rate (BMR) as apposed to the treadmill mode which will use a formula that takes into account your pace.  I would use treadmill run mode - even though you are brisk walking it shuold pick up on this.  You may need to calibrate your stride length if your mileage is way off which there are many tutorials.  The watch uses a fairly established formula to calculate calories burned which can be found here:

http://www.runnersworld.com/tools/calories-burned-calculator

The treadmill is using the same equation so I'm guessing you are closer to 300 calories.  On average you burn about 100 calories per mile which can go up if you are really running and or heavier.  But make sure you put your watch into the right mode!

[trainer]

Just to add more information to all of this, cardio machines can be off by 20% easily each time you use them. Things like: how old is the machine, how often is it maintained, how many people use it, is it a high quality machine or low, all go into the equation. I work in a gym and I have seen machines off by over 20% over the course of the day or even within the same workout/same client. I never use the machine information for my clients! Most accurate is a chest strap HRM, next is a device that knows your personal stats (like a fitbit) that is worn on your torso, third is a wrist device (like fitbit) that knows your personal stats (they are less reliable because they get confused by things like holding onto the handrail, although the new fitbits that also measure HR seem to be pretty reliable (I have no personal experience with those yet). So, I'd say make sure your information in your fitbit profile is accurate for you personally and then go by what it says over time. Any given session might be a bit off but over time you will have a pretty accurate average to rely on. That is how I use mine, I pay attention to weekly averages.

[Heybales]

---

@Solannis wrote:

I am hoping someone out there can help me answer this question. The basic question is: which is more likely an accurate account of calorie burned when spending an hour on a treadmill: My Fitbit Surge or the treadmill's recount of calories burned at the end of my "session?"

Here is the background:

I am using a Lifestyle treadmill found in my company's gym. This is a gym/professional model, not a home unit. Has the TV up top and the full LCD display that lets me browse the web, review my workout stats, etc.

I do a standard workout on the treadmill: 60 minutes at a set speed (these days, 3.6 mph) with 0% incline, then a 5 minute "cooldown" where the treadmill drops my speed by 0.5 mph each minute for the 5 minutes (ending speed: 1.1 mph). At the start of this same workout, just before I step on the treadmill, I select and start an "exercise" on my Fitbit surge that does not use GPS and only collects heart rate information. When the treadmill stops, I stop the exercise on my Fitbit as well.

I do not enter my weight/height into the treadmill, but I did put that information into my Fitbit (via the website and the app). I do not hold the handles of the treadmill to monitor my heart rate at any point (in fact, I don't touch the treadmill at all with my hands, only my feet).

At the end of the workout, the treadmill tells me I burned 324 calories. My fitbit, however, tells me that I burned about 1,200 calories (varies a bit from workout to workout). That's quite a delta. Which one should I be using to account for my actual calories burned? The treadmill doesn't know my weight or height or stride, the fitbit doesn't know my speed or my stride; clearly they are both missing data, so how much can I trust their calculations?

Here's (what I think is) a bonus question: Since the Fitbit doesn't know how fast I am moving (2.5 vs 3.6 or any other speed), and it doesn't know my incline (which, at present I don't have/use one, but I could in the near future), how accurate (or even moderately close) is the Fitbit likely to be (just in general) when I use the treadmill? Or an elliptical? Or a stair climber? I don't care about or expect step-for-step accuracy, but based on the delta I am already seeing as described above, how close is the Fitbit to "truth?"

---

Test both.

But if the treadmill doesn't have your weight, forget it, worthless.

But HRM could also be inflating by healthy amount, 30% more is not unheard of with even a better HRM.

http://www.myfitnesspal.com/topics/show/459580-polar-hrm-calorie-burn-estimate-accuracy-study

The formula for calorie burn on treadmill is very accurate, because treadmill has been used the most in research studies and therefore tested out the wahzoo.

More accurate than HRM actually.

Here's how to test. Hope you can read this.

http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

Even better accuracy to the calculator linked on that page.

In your Fitbit daily burn graph per 5 min, take the 5 min block burn amount when non-moving/sleeping, divide by 5, and that is your per minute calorie burn.

When the calculator mentions the METS value for your pace/incline walk, take your per min burn x METS x min of the walk for best calculation.

[lonerchick]

You burned 1200 calories from an hour on the treadmill? Are you sure this is not your daily total as of that time? Assuming you workout the same time every day.

[Solannis]

Hi DB,

The treadmill only asked my weight, and I put it in, and the numbers it gave me today were no different than the ones I had previously, which makes me suspicious about how accurate the numbers are to begin with.

As far as Treadmill Run Mode goes, I will use that tomorrow and see if those results are any different than what I have already received.

Lastly, I cannot get the link to work properly in either Chrome or Safari on my iMac. I can enter all the information and I see the little circle next to the Please Wait, but nothing happens. I turned off pop-up blocking as well. Not sure what the deal is there, but thought you should have that feedback.

[Solannis]

Hi lonerchick,

According to my Fitbit workout, I burn an average of 1,200 calories per "workout" where my "workout" is just a workout mode that does not include GPS. When in those modes, the Fitbit only counts the activity during the workout, nothing pre- or post-workout. I do always work out at the same time: 6:00 a.m. to 7:05 a.m. give or take a few minutes. Prior to 6:00 a.m., I take very few steps from my house to my car, my car to my office, and my office to my gym. Less than 100 total steps, I believe. So I doubt that -- even if workout mode accounted for those steps -- any of those prior steps would have that much of an impact.

Per a suggestion from another reply, I am going to use the Run - Treadmill mode tomorrow and see if that generates anything different, and will post back here with what I find.

[Solannis]

Hi trainer,

When you say machines are off by 20%, do you mean 20% lower than they should be or 20% higher than they should be? The specific machine I am using is the same one I've seen in 24-Hour fitness locations previously. I didn't catch the exact model this morning, but I will do so tomorrow just for giggles. I haven't really bothered with the chest straps because, to be perfectly honest, I am not THAT much into 100% accuracy or as close as those things get. I am just trying to figure out why my fitbit says one number (1,200) and the machine says another (324) and why there is such a SIGNIFICANT delta (far more than 20% in any direciton) between the two. It would be one thing if they were 20% within range of each other; then I'd probably care a lot less. But with a delta of ~900 calories, I figured it was worth it to ask what the deal was.

I see friends updating various apps saying they were on an elipitical for 45 minutes and burned 570+ calories, so that makes things even more confusing for me.

I hope to get this dialed in and figured out soon.

[Solannis]

Hi Heybales,

Okay, let's take a look at my data based on what you have described and using the Walk/Run Metabolic Calculator you linked to. Here is what I put in and got out:

Inputs:

Mode: Walk

Speed: 3.6 mph

Grade: 0 (no incline at all)

-

Energy: Gross (not sure why I would want gross vs net, so I stuck with the default)

Body weight: 262.2

Duration: 65 minutes

Outputs:

METs: 3.8 (What is a METs? Or a MET?)

VO2: 13.1 (What is a VO2?)

Calories: 509

To follow the rest of your suggestion:

Fitbit daily burn graph 5-min non-moving/non-sleep value: 7.3

Above value / 5 = 1.46

Per min burn (1.46) x METs (3.8) x treadmill minutes (70) = 388

Treadmill reported: 379

Web calculator reported: 509

Not much of a delta between formula burn and treadmill report, but still a good delta between both of those and the web calculator report.

Is this what you would expect to see, given the data? Which is (more) accurate?

[dbanderson1]

@Solannis that looks more accurate:

essentially "net" is the total calories - calories from your basal metabolic rate... so what can actually be attributed to the exercise.  METs are merely a measure of energy, mainly used by exercise scientists.  Originally, 1 MET was considered as the Resting Metabolic Rate (RMR) obtained during quiet sitting. MET values of activities range from 0.9 (sleeping) to 23 (running at 22.5 km/h or a 4:17 mile pace).  VO2 is oxygen consumption... elete runners can guage performance by being able to use oxygen more efficiently to traning adaptations.  The delta between the treadmill and the net calculator is due to the fact that one is probably reporting gross while the other is net (not including what your body would have burned if you were at MET 1 [resting])  Hope that helps.

So based off the information you are providing I would guess that you are burning 380 calories due to exercise and the another 100-200 based off of inate bodily needs.

Another article that may help:

http://www.runnersworld.com/weight-loss/how-many-calories-are-you-really-burning?page=single

I wouldn't worry about METS/VO2 much... more jargon for exercise physiologist and competitive runners.  

[Heybales]

---

@Solannis wrote:

Hi DB,

The treadmill only asked my weight, and I put it in, and the numbers it gave me today were no different than the ones I had previously, which makes me suspicious about how accurate the numbers are to begin with.

As far as Treadmill Run Mode goes, I will use that tomorrow and see if those results are any different than what I have already received.

Lastly, I cannot get the link to work properly in either Chrome or Safari on my iMac. I can enter all the information and I see the little circle next to the Please Wait, but nothing happens. I turned off pop-up blocking as well. Not sure what the deal is there, but thought you should have that feedback.

---

Weight is usually all you need really for about best accuracy of calorie burn walking flat 2 - 4 mph, and running 4 - 6.3 mph.

Incline and faster starts losing accuracy, because the personal differences in form starting making bigger impacts to calories burned.

So if you did x pace at y time with z weight each time - yes the calories burn should be the same.

[Heybales]

---

@Solannis wrote:

Hi Heybales,

Okay, let's take a look at my data based on what you have described and using the Walk/Run Metabolic Calculator you linked to. Here is what I put in and got out:

Inputs:

Mode: Walk

Speed: 3.6 mph

Grade: 0 (no incline at all)

-

Energy: Gross (not sure why I would want gross vs net, so I stuck with the default)

Body weight: 262.2

Duration: 65 minutes

Outputs:

METs: 3.8 (What is a METs? Or a MET?)

VO2: 13.1 (What is a VO2?)

Calories: 509

To follow the rest of your suggestion:

Fitbit daily burn graph 5-min non-moving/non-sleep value: 7.3

Above value / 5 = 1.46

Per min burn (1.46) x METs (3.8) x treadmill minutes (70) = 388

Treadmill reported: 379

Web calculator reported: 509

Not much of a delta between formula burn and treadmill report, but still a good delta between both of those and the web calculator report.

Is this what you would expect to see, given the data? Which is (more) accurate?

---

Great data. Gross was correct option to use.

The METS x your personally found resting calorie burn is most accurate, and it appears close to what treadmill saw.

The studies that made that formula ended with VO2 actually that the runners/walkers had, and then that is converted to METS based on the generally found principle most people have a resting VO2 (oxygen consumpution) of 3.5.

So the METS you could say is based on the studies, and is the result of the studies taken down to a value that could then be applied to anyone.

The problem is the actual calories burned using that 3.5 mL of oxygen per kg per min varies.

So the calculator is indeed making some assumptions converting the METS back to calorie burn, and as you can tell, there isn't enough stats for resting metabolism calculations (gender, height, age), so it uses a default 1.2 cal / kg / hr conversion.

Hence the reason I had you calculate your resting calorie burn per min. Which is better than default amount.

And indeed, those estimates really start to spread as mass goes up. I'm surpised it's that much difference actually.

Sounds like you may want to trust the treadmill, and manually log those workouts.

Now, Fitbit step based calculations actually attempt to do exactly what you did, they have resting calorie burn, they have formula, shoot, even their database entries are by METS for proper math.

I'm not sure why the device was so high.

Unless it had distance way off.

Or it's HR based device estimate, and for now you are out of shape with greatly inflated HR while doing it.

Or you had a double epresso prior to workout! Just joking, studies have shown little to no effect, but other meds could.

[Knowledge]

The treadmill does not use HR data to calculate calorie burn while the Surge does. I would trust the Surge because of my personal experience the calorie burn vs weight loss has been spot on for me the last 7 weeks. Most people on these forums that have a chest strap HR monitor have compared to the Surge and found that usually the Surge underestimates calorie burn because the HR monitor doesn't always go up to the highest HR that the strap can track (depending on the accuracy). However I have never seen any one of them say it overestimated calorie burn. I would trust your Surge over the treadmill specifically because of the HR data being a key component here. The treadmill does not incorporate the HR data, even if you hold the bars! That piece of information is only given if you're curious but has no benefit to the treadmill calculations.

[Davenna]

I wear a Pulsar watch at the gym...much more accurate as far as heartrate and calorie burn.  You can enter your sex, age and weight, so the watch is calculating based on the correct variables.

[Heybales]

---

@Davenna wrote:

I wear a Pulsar watch at the gym...much more accurate as far as heartrate and calorie burn.  You can enter your sex, age and weight, so the watch is calculating based on the correct variables.

---

That's not actually enough stats, it's using those bare minimum stats to assume stats that are actually used to calculate calories - VO2max and HRmax.

And I'm sure they are not using the best of formula either.

But you might test it.

http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

And here is the lab testing of a nice expensive Polar with self-tests, before using lab measured stats, and the inaccuracy in both cases. Not pretty if you think your HRM is much more accurate.

http://www.myfitnesspal.com/topics/show/459580-polar-hrm-calorie-burn-estimate-accuracy-study

[DominicJ]

The fitbit should be more accurate, because its measuring your actual change in heart rate, but burning 1200 calories in an hour is, whilst possible, unlikely unless you are running a competitive marathon or a you are carrying a baby elephant.

Using treadmill counters.

My fastest 5k (32:15) burnt 371cal

However, Ive ran slower ones ( faster sprints with longer recoveries) and burnt over 500cal

There is a bias for "harder" excercise using more calories which the fitbit will be better at tracking.

[dancefoxtrot]

When I'm dancing ballroom dance like waltz or foxtrot and I'm in closed position, that is with my left hand on his bicep it doesn't track all the steps because my arm is not swinging.

[higg002]

you are not  exercizing... you are  just above the sleep mode. why  bother  with a fitbit ?