Surge - New User - First thoughts, first walk, calories

[MarkSR]

Hi. New user to the Surge. Prior to using the Surge I have been using my S6 phone (S Health) and manual calculation (using simple stop watch etc). I am not really into fitness, but need more exercise and to control what I eat and drink. Anyway, so far generally impressed with the watch and its integration into the Fitbit app (S6) and also using the web interface (where I am now). Generally the data it has produced so far is more or less in keeping with my manual BP monitor (S6), miles walked (S6), steps (S6) and so on. So far so good. I must admit the whole issue with Calories and how that data is displayed on the app somewhat confuses me, but I will read up on that. However, the one issue I do have (and I think others do....) is in relation to calorie burn during an activity.

So, I have checked my profile is correct. I started out on a walk and walked 3.31 miles in 57 minutes. My S6 reported I had burned 351 calories, whereas the Surge reported a mind blowing 926 calories (I wish!). At first I thought that this might be gross calories, or maybe "more accurate" because of the heart rate (which was 60 BPM at rest and on average 160 during the walk, with a peak 175). Anyway, I have used what I think is a reliable on line calculator (which uses standard internationally recognised equations). Using my weight (95kg), my height (5ft 10), my sex (male), my age of 45 and the walking data - it calculates GROSS calories burned as being: 443.  It then calculates the NET as being 357. I am sure this is about right, as for some time my calories burn per mile on a typical walk have been about 100 calories / mile.

Now my S6 that I took out today as well - showed 351 calories - which is very similar to what I calculated manually. It also takes into account the above data (age, height etc). So on that basis I have two different methods (S6 and manual calculaton) which gives me more or less the same result.

So, despite my general praise of the Surge, what I am trying to work out is what an earth (!) is it doing when it calculates calories of 926 !!!  Its not even gross - it seems totally over the top. Anyone else seeing this?!

I should add that when I set off I could only choose "Workout" on the Surge (Run etc was not relevant). When I got back onto the web interface I changed it to "walk" and it then gave me distance (which was not displayed when I had it set to "Workout"). I am wondering if the "Workout" setting on the Surge is not the correct setting for calculating calories burned during walking - in which case I am wondering what is better (Run?), or indeed if the different settings change how the calorie calculation is made of a specific activity?

cheers

Mark

[Chris1963 · Accepted solution]

It's quite possible the workout mode showed higher burn rate for calories. Perhaps a moderator could confirm that different algorithms are used based on the expected intensity of an exercise. A workout would use more body parts more actively than walking even if HR's are similar. I guess HR is not the sole contributor to calorie burn calculations?

Anyway...why not use the Walk mode? Either GPS driven or auto? Left button press once, Right button press once and walk should appear and a GPS search starts.

Alternatively look in your settings to see which activities are selected and either tick or delete those you don't want.

900+ is absurd though. I've found calories seem to overestimate for walks, they haverecently been much more accurate for cycling ie matching a Polar app via a chestrap and just using some different manual calcs on fitness websites. 

[MarkSR]

Many thanks!

I think I had actually worked this out before seeing your reply, but very much appreciated your quick response. The issue was that with a fresh Surge "walk" was not an option, and since I did not want to run I thought "workout" might be the best generic option. Later I wondered why I could not see a map of my walk, and then noted that "workout" does not use GPS! ... Then looking at the dash board on me PC and selecting my Surge is realised I could select "walk" as a menu option. So, I have not tested this yet, but given what you have said I am betting that if I choose "walk" next time the calories will be much more on track!.

cheers

Mark

[Chris1963]

Hi, no problem. Don't forget also to set up your personal info and also other preferences such as activities (up to 7 I think) that you will use. Also you may not be aware some activities such as running, walking, cycling etc automatically log if you do them for over a set amount of time (mine are set at 10 mins) which means you dont have to drain the battery using GPS  on say a 20 min walk to the shops or forget to turn it on. It'll not show a map of your route but will give HR, calories and distance (assuming your stride length is input correctly)  

https://www.fitbit.com/settings/device

https://www.fitbit.com/user/profile/edit

[MarkSR]

Evening. OK, so I have now checked things are set up.

Did a 1 mile walk tonight in 30 minutes (slow walk to pub). The Surge said 170 calories. That in my view is still too high, but not as mad as earlier. My other method gave me 160 calories (GROSS). This is much nearer the Surge. So I believe that the the calorie burn provided by the Surge is GROSS not NET. Does tham make sense and match your own observations?

rgs

MArk

[Chris1963]

Still sounds high I agree. Mine reads about 130 a mile on a 103bpm heart rate, brisk walk. I still think that is high, I reckon 100 is nearer the mark. As do most other fitness websites.
On the bike it's about right or at least compares favourably with what others say.
As far as I know it includes calories you'd burn just sitting around if that's what you mean by gross.
Keep an eye on your HR too...the Surge ain't that accurate when there are rapid changes. It copes ok resting or walking but is a little erratic if you push it!

[MarkSR]

Morning 🙂

OK, overnight I think I have sussed what is going on. In some ways it does make sense, but I do not that Fitbit is that clear about this... takes deep breathe...  I think everything it does it worked out on BMR (energy to stay alive) PLUS weight maintenance calories (general activity) = total calories to stay at same weight. If do this using a favourite calculator (based on 45 years, 171cm height, male, 95 kg and my estimate of rest plus light activity) then I get  BMR = 1924 calories and Total  = 2886 calories (to stay same weight). I am not very active (I am going to sort that), but the total is very close to Fitbit. I thought it was too high, but now when it says, for example, you have some 2150 calories left (I thought too high at first), that makes since when I have selected a deficit of -750 calories a day ....

The next thing is how it shows this data. Unlike my calculation above which is fixed (by my own estimation of activity including rest), it calculates this 24/7. In fact I would not be surprised if the software "learns" this over a few days of use, or it might use a rolling average. Either way it is calculating the weight maintenance value which will change depending on how busy / active you are. That explains how the calorie deficit etc can go up and down.

So, if I assume 2886 is about right, then every hour I am burning : 120 calories. Therefore in 30 minutes it is 60 calories. As I noted last night, I think it is working everything in GROSS values - I thought that was BMR, but now I think it is BMR plus weight maintenance. So you noted, and I agree, that walking a mile will produce a net burn of perhaps 100 calories (this will vary a bit according to age, sex, height etc).  So the figures I got last night, say around 160 calories) for the walk actually make complete sense  : 100 calories for walk, plus 60 calories burned anyway = 160......

At the moment I cannot work out in my head if this is a good way of explaining this, and if the Fitbit approach makes good sense?! I think most peeps, myself included, have just been used to being told 'eat that many calories and you will lose this much'. If anything, perhaps Fitbit is giving too much info? Either way, and I need to test more over the coming days, I do not actually think it has got the calories wrong, indeed I think a first look shows its almost totally bang on....

Mark

[Chris1963]

Hi, I have thought about this previously but I'm not convinced. My BMR is about the same, around 1750 or so. Of course any activity, even just sitting typing uses more as you know. The displayed calories on a walk include the 24 hour BMR figure divided by the length of time of the walk so 1 hour is around 70 cals. I don't think it has anything to do with your TDEE (apparently this is total daily energy expenditure). I think its used when you are trying for say a 1000 calorie a day deficit and enter food eaten - activity + BMR to give you a running allowance.

I'm pretty sure the calories displayed is BMR + exercise, in which case it overreads in my experience, particularly on walks. Cycling (my only other activity really) now seems to be spot on since I moved the Surge to my other wrist! 

There is a ton of stuff if you search the forums but perhaps a moderator may explain how its measured after age, height, weight data is input.

In the meantime heres an example discussion....

https://community.fitbit.com/t5/Charge-HR/Why-are-BMR-calories-burned-included-in-a-manually-tracked...

[MarkSR]

Would be good to know how this all works!! My suggestion is just based on
observations compared with my phone and manual calcs. Aside, I think I
need to adjust my stride length too as my steps is I think over estimating
my distance!!. Rgs Mark

[MarkSR]

Hmmm some more interesting results (this is such a time waster - in a good way). I wanted to calibrate my stride today. So I walked a known distance and then used the divided steps into total distance - almost bang on  - so I am average! Which makes be wander if too many 'half steps' or other shuffles are being recorded as I appear to have walked nearly a 1.5 miles today to and from the car, around the house, at a clients premises, and other general places. Maybe I have?! But that sounds a lot of what to me appears to be a rather tame day in terms of exercise of any sort....

However, putting this all together..... I am reasonably confident that my S6 app I have used for some time is reliable and consistent. It displays the information in a totally different way and seems to deal with Net calories. That said the basic BMR plus general movement (fixed on the phone) is more or less the same as that on the Surge, the difference being that the Surge will adjust the general movement in real time.

The upshot of all this - is that when I compare the two apps, with the same foods entered and with the same exertions recorded - the actually calories available to eat (to meet my weight loss) is about the same. This was a surprise which I think indicates I can have some good confidence in the Fitbit. Initially my phone was coming out with a lower value of calories remaining, but this is because it was set to Very LOW  - so the general movement aspect is fixed very low all the time. Clearly this is not the case and this is where the Fitbit Surge does some nice helpful stuff. When I changed my phone setting from Very LOW to "low" the calories remaining were almost identical. A good result!