Burnt calories support?

[GiornoGiovanna2605]

Hi y'all, have just a small question: is there any app that can stimate the amount of calories burnt based from the amount of steps in the bangle js 2? It's not a big deal for me, though it would be a good feature for runners maybe.
Thanks in advance for any answers! ^^

[bobrippling]

I expect we could get a rough estimate if a user were to enter their weight and perhaps other details (maybe via myprofile). @gfwilliams is this something that's come up before?

[thyttan]

There's a previous discussion here: https://github.com/orgs/espruino/discussions/6359

Calories mentioned on the forum: https://github.com/orgs/espruino/discussions/categories/bangle-js?discussions_q=is%3Aopen+category%3ABangle.js+calories

[gfwilliams]

Thanks @thyttan! Looks like there is already weight in myprofile so it could be pretty easy to add.

I wonder where it would make sense to do it? As its own app? Or I guess the health app could have an option to show it?

[GiornoGiovanna2605]

Yea maybe the health app could be a good option

[RKBoss6]

I would also like to see this happen, maybe by coupling steps, hrm and movement?

This link came up in a search that has a formula for calories: here.
It looks like you first need to calculate basal metabolic rate from height, weight, age, and gender, then determine the activity per day/interval, and update it accordingly

[RKBoss6]

I wonder where it would make sense to do it? As its own app? Or I guess the health app could have an option to show it?

I think having it as a menu option in health will help, that points to the myprofile page.

I've researched, and have narrowed it down to a set of calculations for bangle.js:

1. get the user's resting heart rate (this can be done by the user manually with the health app getting a user-triggered reading with the user being still)
2. get user's weight
3. every health interval, calculate the HRR ( (current HR-rest HR)/(max HR - rest HR) )
4. get the coefficient of energy from that reading ( 10*HRR+1)
5. Use the HRR coefficient and average that with the calculated coefficient of energy from steps (0.04*steps/min)+1.25
6. use the newly averaged energy spent coefficient and calculate calories burned! (energy coefficient * weight in kg *duration in hours)
   (of course there are simpler methods, but not nearly as accurate as this one can be.)
   a question I had: is the event 'health' emitted by the health app, or is it a system level event? If it's from the health app, we can add calories and resting heart rate...

[bobrippling]

Sounds like a plan - the health event is firmware-level

[gfwilliams]

Looks like the My Profile app already stores weight and some other stuff, so it's really just a matter of using that: https://banglejs.com/apps/?id=myprofile

You shouldn't have to store any of the burnt calories data either - you can just work it out on demand from the stored health data before you render - so I guess this could just be an extra menu that appears in the Health app if you have My Profile installed

[RKBoss6]

I'm working on RHR measurement, is it better to save the measurement to a health.json file, or use the existing myprofile.json file? Also, once calorie detection is in, is it possible to add calories burned in an interval to the health event in fw?

[RKBoss6]

Ok, I've just created a PR #4121 to add RHR and prepare for calorie calculations. Right now it saves to myprofile.json

You shouldn't have to store any of the burnt calories data either - you can just work it out on demand from the stored health data before you render - so I guess this could just be an extra menu that appears in the Health app if you have My Profile installed

I think saving it is a good idea, since the web interface just loads the data and reads it, meaning calories won't show up. How exactly does one go about doing that? I'm unaccustomed to the health app's data methods, so help is appreciated on that front.

[gfwilliams]

I guess myprofile makes sense as that's where the other body-related info is.

is it possible to add calories burned in an interval to the health event in fw?

Not without changing the file - and I don't think we should be wasting our very precious flash by storing data that we can just generate on the fly. Also what if the algorithm changes or someone maybe adds/changes their info and then wants to see what energy they used before they made the setting? Once written the data in the health lib is 'locked in'.

It's quite likely we could allow the health app's interface.html file to also load the lib.js such that it can do the calculations itself using the same code?

[RKBoss6]

Cool, I'll get back here with a small prototype of the calorie calculations

[RKBoss6]

Also, just another question, according to the docs, Bangle.getHealthStatus('day'); returns hr as the best sample in the day. Would it make more sense if it takes the best samples and averages them to provide an average hr, instead of one where the reading is the best?

[gfwilliams]

We're just using the same code to handle 10 minute interval/day. To be honest it doesn't really matter, because nobody really uses HRM in that call anyway - the call is there pretty much just for step counting which wants the steps done that day.

The actual daily HRM that is stored by the health library is averaged as you suggest: https://github.com/espruino/BangleApps/blob/master/apps/health/boot.js#L97-L102

So if you query the health lib for HRM per day for previous days, you get an average

[RKBoss6]

Just added the first iteration of calorie tracking in #4121! Take a look and see what's up on my app loader