
Show HN: Happy Scale – Use moving averages for accurate weight loss predictions - rooster8
http://happyscale.com/
======
kevin
Whoa, this app is feature packed. It's all pretty straight forward except for
this part in the beginning :

[http://cl.ly/image/1d3q2Q3S0029](http://cl.ly/image/1d3q2Q3S0029)

Why would I click on the hamburger menu icon to add a weight? Seems like I
should hit the + button on the top right? In fact, it seems incorrect since it
did what I expected, which was slide out the navigation. The + button, did ask
me to add weight.

One thing I wanted (and maybe you have it?) was the ability to set a regular
notification to remind me to weigh myself. Also, for the deluxe edition what
are the other features besides removing the ads? I couldn't find what those
would be. It showed up a nice list of them when I hit the button, but know
that most people are going to be hesitant to do so. I'm not sure if Apple
would allow it, but if you could integrate the question to upgrade into your
onboard slideshow, I'd bet you'd get higher conversion. The way it is, it's
pretty buried in there and this is the kind of app that people won't upgrade
until they have several days worth of data to see if it's worth it. Chances
are your app is going to tell them that they're bad at losing weight. They're
going to be the most motivated and hopeful right when they downloaded it. Hope
is a good place for conversion in my opinion.

Also, for the My Weight Goals, I didn't understand why it defaulted to Track
Using : Actual Weights. Isn't the point to have it track using Moving Avg
Weights? I just wasn't sure why you defaulted to this.

Thanks for sharing!

~~~
shampine
I think that is an error in the content, it says hit the triple line button in
the upper right. Well one half of that is wrong, so if the + button did allow
you to add a weight, then it meant to say plus instead of triple line.

~~~
rooster8
Exactly. I changed this copy in the last build when I added HealthKit, so I'm
hoping this slip up is at least limited in how long it's been there.

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rooster8
Hi HN!

Happy Scale helps people who are losing weight to redefine their relationship
with the scale. By using their daily weigh-in as a single data point in a
moving average instead of a source of truth, you can see daily weight loss
progress in the app even when your scale weight plateaus for a few days. Over
time, you become desensitized to the horror of a bad weigh-in and can avoid
discouragement during the tender moments of building your new lifestyle
habits.

I created this iOS app because I would be devastated in the first few days of
a diet when I hopped on the scale and saw a number that was higher than my
starting weight. I went on to learn that there are many factors that can cause
fluctuations of a few pounds in our weight from day to day (glycogen stores,
water retention, food in the belly, etc.), and using a moving average is a
convenient way to neutralize these factors.

I've been working on this as a nights and weekends project for a bit over 4
years. I have some big ideas for where I'd like to take it in the future, but
I'd love to get your feedback on where it is today!

~~~
yurymik
Import function seems to be broken on iOS 9.0 beta 13A4325c:

[http://imgur.com/cHs5G1t](http://imgur.com/cHs5G1t)

~~~
rooster8
Thanks for letting me know! If you'd like me to let you know when it's fixed,
email me at support@happyscale.com.

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yaddayadda
For Android users, I've been using Libra for several years now and enjoy that
I can customize the moving average.

[http://www.appbrain.com/app/libra-weight-
manager/net.cachapa...](http://www.appbrain.com/app/libra-weight-
manager/net.cachapa.libra)

[https://play.google.com/store/apps/details?id=net.cachapa.li...](https://play.google.com/store/apps/details?id=net.cachapa.libra)

~~~
rooster8
I've never used this app first-hand, but it's the one I recommend to users
when they ask about an Android version. I didn't know they let you customize
the moving average, so I'll have to check that out.

If you wouldn't mind sharing, how do they let you customize it, and what do
you enjoy about that?

~~~
yaddayadda
Under 'Preferences'[1] there is an 'Advanced Preferences'. In Advanced
Preferences, there are two relevant settings: Smoothing Days and Forecast
days. The differences aren't clearly delineated, so when I first started using
Libra (several years ago), I ended up experimenting for several weeks.

The explanation for smoothing days is that it "[controls] how strongly each
weight value affects the trend". It takes an positive integer value or 0. The
recommended value is 7, but I ended up with 14. With higher values, both the
forecast line and average line tend to be less dependent on recent weights and
average out over a longer period.

The forecast days "[control] how many days to use for the forecast
calculation. It doesn't specify what the acceptable range is, simply that the
minimum value is 2 and the recommended value is 7. I ended up with a 14 here
also. This value only impacts the forecast line, not the average line.

[1] On my phone, reached via Android's hamburger physical button. [2] Reached
via a button that looks like the ai-settings icon from the
[http://www.androidicons.com/](http://www.androidicons.com/) set.

~~~
rooster8
So you liked that you could customize it to be more responsive to recent
weight changes... interesting.

I do also have an advanced settings section for the forecast calculation, but
it's good to know there's interest in controlling the MV factors too. Thanks
for the feedback!

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tl
From my experience, using a moving average works really well to track weight.
I am repeatedly amazed that more apps don't have something like this
considering Hacker's Diet[1] was doing it over a decade ago.

[1]
[http://www.fourmilab.ch/hackdiet/online/hdo.html](http://www.fourmilab.ch/hackdiet/online/hdo.html)

~~~
jjp
You could also take a look at trendweight.com if you are using Fitbit Aria or
Withings scales and want the Hacker Diet trends.

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cmsj
Very nice app! Thanks for putting decent HealthKit toggles in the app itself.
I'm quite choosy about which apps can read HK data and which can write, and
many of them are not good at making it obvious if they can cope with that!

~~~
rooster8
Thanks! It's always a balance between keeping it simple and giving users
control. I'm glad to hear from the segment that appreciates that control.

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krrrh
Looks like a nicer UI than the withings app. Any thoughts about adding bf%? My
#1 feature request for an app like this would be to see trend lines for LBM kg
and Total Fat kg on one chart.

~~~
rooster8
I actually really like the Withings UI, so I take that as high praise.

Yes, Body Fat % is a pretty important thing on my list. I don't have it
scheduled for the next release, but I do hope to get it into one of the next
couple of releases.

~~~
krrrh
Just to add a bit more feedback here, the part that withings fails me on is
not exposing Fat and LBM in weight terms. If my goal is to maintain LBM and
see Fat % go down over several weeks it makes it difficult to determine if
that last 2% of bf% drop was too fast (read: too much LBM loss) without
actually exporting the data and calculating things by hand. They used to make
these variables available in their old web ui, but they aren't available in
the app. It feels a bit dumbed down.

They also allow you to set a weight goal, but not a bf% goal, which is so
confusing when their marquee product includes a body fat analyzer. For a lot
of people who buy these scales to help gauge recomposition efforts the goal
over time is to keep their weight the same but see the bf% go down.

------
jasmcole
What's the 'advanced math' used for the moving average? Some form of
convolutional filter?

~~~
rooster8
The simple answer is an exponential moving average, but there's some
additional stuff to compensate for the lag associated with using a moving
average on a downward-trending or upward-trending dataset.

