Trendweight

[A_Lurker]

A number of us talk about trendweight.com and how it's important to look at your overall progress instead of a specific day, week, month.  My stats are pretty much open and I post about mine every week, so I thought I'd share my graph at the moment.  If others want to share theirs feel free to cut off the far right and blank out the actual numbers. The main idea is to look at the overall changes, not the numbers.

My trend is currently 1.2 above my actual, but it gives a good snapshot of my overall loss.  There are steeper and shallower slopes, but the overall is down.  You can see spikes where the grey line (actual) crosses the trendline, but again, the overall picture is the important thing.  I think of it as smoothing the ups and downs.  Sharing my 3 months graph:

If you look at December I coasted and even went up one week.  November showed some wild swings - meals out mostly.  In the end though it's about long term commitment to working on a better way to live.  I guess what I'm saying is that you can have a bad day, week or month and you can still continue on.

[Dominique]

I’m another big fan of TrendWeight. I had been tracking my weight since June 2013 (when I purchased my Fitbit Aria smartscale), but I only heard about TrendWeight about one year ago. It’s a lot better than the graphs displayed inside Fitbit. For instance, this is my weight for the past three months in Fitbit:

 Weight, 3 months, Fitbit

Only 13 data points, and weight is displayed in increments of 2 kg, which makes it harder to read). This is what I get with TrendWeight for the same period:

Weight, 3 months, TrendWeight

I get individual data points for every single day (with increments of 1 kg), plus the red curve drawn by TrendWeight, as well as my projected weight. A lot more useful IMO.

This is how Fitbit displays the entire period tracked (4 years):

Weight, all, Fitbit

 And this is how TrendWeight displays it:

 Weight, All, TrendWeight

TrendWeight can be used both if you have a smartscale that can sync to your Fitbit account (this is the case of the Fitbit Aria, but also of smartscales from Withings and Weight Gurus) and if you have a regular scale (in which case you need to manually enter your weigh-ins in Fitbit). As I mentioned above, I’m using a Fitbit Aria. I believe @A_Lurker is using a regular scale.

[A_Lurker]

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@Dominique wrote:

I believe @A_Lurker is using a regular scale.

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Yes, I still manually log my weight.  I may step on the scale during the week but I don't bother with daily anymore.  I now log just once a week.

[almost_where]

I really like the way trendweight does their charts. I don't dislike fitbits per se but i think I might start to use the trendweight site as well going forward. 

[RachelShrinks]

I really like trendweight, too (thanks @A_Lurker and @Dominique for turning me on to it), but I have a question: Currently, it's showing my trend weight at about 3 pounds above my current weight... Anyone know why it's so high? I'm assuming it's because I only just started and have been losing weight so quickly (7.2 pounds in the last month) after not losing weight at all for a long time.

trendweight, 3 months

[UVcat]

@RachelShrinks wrote:

I really like trendweight, too (thanks @A_Lurker and @Dominique for turning me on to it), but I have a question: Currently, it's showing my trend weight at about 3 pounds above my current weight... Anyone know why it's so high? I'm assuming it's because I only just started and have been losing weight so quickly (7.2 pounds in the last month) after not losing weight at all for a long time.

trendweight, 3 months

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I think Trendweight just takes a simple moving average, though I'm not sure over what time period (probably at least a few weeks?). Since you are losing weight, the average (and therefore the trendweight) is going to be higher than the last data point (current weight). The faster you are losing weight, the larger the discrepency is going to be. I guess this means Trendweight sort of underestimates your weight loss while you're in weight loss mode, but it does also smooth out the noise.

For comparison, I'm pretty much in maintenance, so you can see from my 3-month graph below that the trendline always lags above the scale reading if my weight is going down and likewise the trendweight is lower than my current weight if my weight has been going up.

Hope that helps!

-UVc

[GershonSurge]

All the details are at this site: https://www.fourmilab.ch/hackdiet/.

[Dominique]

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@UVcat wrote:

I think Trendweight just takes a simple moving average, though I'm not sure over what time period (probably at least a few weeks?).

Actually, John Walker's The Hacker's Diet (onto which TrendWeight is based) uses an exponentially smoothed moving average.

For the mathematically inclined, this is the chapter that explains the various moving averages (simple, weighted, exponentially smoothed). And this is the chapter on signal and noise (mentioned in the TrendWeight FAQ in the answer to the question: "What mathematical analysis is being used to calculate my trend weight?").

[UVcat]

Thanks for providing links to the underlying algorithm. I was trying to answer @RachelShrinks question about why her trendline was far above her current weight while she is losing weight. The details of the averaging method are probably not that helpful for understanding why this occurs, but maybe she (or someone else) will find them interesting.

-UVc

[JAMIE9999]

im wondering why trendweight says im burning over 1000 calories more than im eating and im down 1.7lbs in a week but when i weigh myself im up 4 lbs?

[Dominique]

@JAMIE9999: when did you start tracking your weight in Fitbit, and how many data points do you have so far? TrendWeight needs a minimum number of data points accumulated over a minimum period of time before it can produce meaningful information.

[JAMIE9999]

@Dominique the first date I put in on Fitbit for my weight was January 1st   On Fitbit graph I have 2 data points on the graph although I've weighed myself every week since so the 17th would have been the 9th time if I counted right.  Trendweight graph is showing from February 6th with 4 weights shown on the graph.

[A_Lurker]

@JAMIE9999- on trendweight you can check two things.  Under settings doublecheck your start date (middle of the page) and when you're on the dashboard page there you want to see if you're looking at 2 Weeks, 4 Weeks, 3 Months, etc.

[katanel]

Hi @A_Lurker,

Nice idea opening this thread 🙂

Thanks to @Dominique I've using trendweight.com since January 1st.

1. I've add weight and body fat daily into Fibit app. I'm using a Tefal scale.

Here is my weight evolution in the last 4 weeks:

I'm on the good way to reach my target of 75kg (last scale value is 77 kg)

2. Not so happy about my body fat measurement - I mean the values have fluctuations:

That's why the webiste has difficulties to find a...trend 🙂

3. Also I'm looking into my Fitbit weight/body fat screens and compare each week average. If it's going down - it's good

4. Next step: probably I'll take weight/bodyfat daily but enter in Fitbit app only the weekly average

5. Trendweight tells me that I will reach my target of 75 kgs around April 1st - huraay!

[A_Lurker]

@katanel- I think the body fat % is affected by water and bodily waste.  I only note this because I've noticed a couple of times that it dropped after a bowel movement.  I snipped out the numbers, but if you look at my bodyfat % when I was weighing daily it was all over the map.  For reference, the horizontal lines are 2% apart.

[katanel]

Hi @A_Lurker

so less water in the body...body fat increases right?

[A_Lurker]

That's what I've seen.  However, this is not a case of weighing yourself, drinking a bunch of water and seeing a change.  We are mostly water so it makes sense that changes in hydration would cause issues.  There's more about how the scales work (and how they vary) about halfway down this page:

https://www.fitnessmusthaves.com/scales/how-do-body-fat-scales-work/