Thursday, 1 January 2009

Body Composition Graph

How to Interpret the Chart

Hover over the flags to see notes on some of the significant weight changes... then on any links in the small box that pops up to see the Twitter or blog posts I wrote at the time.

You can scroll to the left using the scroll bar under the chart to see older data.

I update the online data every few weeks or so.

Background

Each night I am at home (and sober enough) I weigh myself on a set of Tanita scales. I've been doing this since 2005. You may say this is a little obsessive, and you'd probably be right.

The scales have metal plates to measure the electrical resistance through the body, the facility to enter your height and, obviously, they also weigh you. After a few seconds the readout indicates the percentage of your weight that is fat - I believe it uses tables of data based on population averages to infer this.

The percentage fat reading is subject to fluctuation. Room and skin temperature have an effect, as do hydration levels. There may be other factors.

The weight reading is subject to fluctuation too. Hydration levels, recency of bowel movement and water retention (due to fluctuating salt intake) are the three main factors I have observed. The steadiness of the weight line it's a good indication of how regulated (and usually how healthy) my life has been over a given period.

16 comments:

AT22 said...

Pretty cool! I noticed that the fat doesn't seem to directly correlate to the weight. Seems when you do some exciting physical event, the bf drops; when you indulge, it goes up. Is that too simple an inference or have you noticed that?

Oh, the comment boxes over on the left side of the graph get cut off by the left edge line.

Beth Mazur said...

I don't understand the y-axis for weight. On my browser, the scale goes from 10 to 13 lbs, and over three years, your weight has varied just one lb (between 11.5 and 12.5).

Cool use of Google docs tho!

Methuselah said...

AT22 - yes, there do sometimes appear to be patterns like that. The trouble is, there are so many confounding factors that it's hard to know what's genuinely a bf change. For example, when I indulge, in invariably involves high salt foods - so my water retention goes up, but, paradoxically, I suspect I am dehydrated due to the usual involvement of alcohol. And of course I am sometimes dehydrated after races, which would affect the fat reading for reasons other than that I have burned fat during the race. Anyway, the good thing is that the readings are still good for tracking longer term trends, albeit that within the relatively narrow band my readings occupy, the absence of a decimal place on the fat reading makes subtle changes hard to detect.

Yes, I noticed the cutting off of the comments box in the left. It was a tricky one to solve, so I am hoping people will know to scroll the display left to see the comment. Thanks for letting me know though.

Methuselah said...

Beth - well spotted! It's supposed to be Stones... will get that changed. Thanks.

Streeter said...

What do you use to track your weight (besides the scale)?

Methuselah said...

Chris - I just put it into a Google spreadsheet that feeds the chart via some json in the JavaScript.

Methuselah said...

Beth - weight label now fixed to say 'stone' - thanks again for the tip.

Drs. Cynthia and David said...

It looks like all your spikes are accompanied by alcohol (and resulting feed-fest). what about the more rapid declines?

We have one of those scales and do daily measuring too. I have my doubts about it though- if I go run in hot weather and come back and reweigh, I might be two pounds down but it tells me I lost a lot of fat, not water. I know that's not right.

I wonder if the spikes in weight you observe are like a mild form of refeeding syndrome. It's not just glycogen repletion water that adds to the spike, but insulin/carb stimulated volume expansion of all cells, where they take up water, potassium, magnesium and phosphate. In true refeeding syndrome, people can get quite ill and die (heart arrhythmias) from low serum K and Mg. I've never heard of anyone doing a similar study in low or zero carbers to see if there is net uptake of water into cells when they carb binge, but it would explain these short term weight spikes.

Cynthia

Streeter said...

Oh ok. I guess I'm also curious about the JS library you are using to display the graph correlated with the various events.

Methuselah said...

Cynthia the rapid declines always follow the rapid ascents, and I think are a result of the sodium balance being restored when I return to non-salty foods, as well as the overall volume of food in my system being reduced.

Your points in the final paragraph will need some consideration - they sound very plausible. I will do a little pondering (and reading) - thanks for the thoughts.

Methuselah said...

Streeter - I don't use a JS library - it's all custom code I wrote. The only JS library is the AJAX / Json stuff. My code pulls in the dataset from the spreadsheet then creates the chart images using the chart API... at the same time as iterating the data to pass to the chart API it looks for comments in the third spreadsheet column then adds absolutely positioned divs to the layer containing the chart images at the appropriate place according to the data item the comment was adjacent to. Hope his makes sense!

Streeter said...

Yep, it does. Thanks for the follow ups.

Drs. Cynthia and David said...

I guess you could just binge on carbs without the salt and see what happens! (is that possible?)

also, you may know the answer to this question- I started some weight training, and even though my diet has been pretty clean, and I expected my weight to go down again after the holidays, I'm gaining weight rather than losing. Arg! What do yo think is happening? Thanks.

Cynthia

Methuselah said...

Cynthia - I have thought about that before but never done it. If I were going to do it sober, I think I'd go for porridge (oatmeal). It's one of teh more inoffensive complex carbs and the thing I miss most since going paleo. I'll do a post if I decide to have a go. Perhaps next time I have a race I'll do it beforehand, because then I'll feel like it's going to get used.

The obvious thing would be that your weight gain is muscle - but of course you would have thought about that. The scales we use to measure composition are not really accurate enough to pick up short term composition changes though, are they? Do you think it could be an increase in muscle with no change in body fat? Another thought - has the weight training displaced any other activity and therefore changed your overall energy output? That said, I would expect weight training to affect your appetite less than cardiovascular exercise, so displacement of the latter by the former shouldn't lead to weight gain...

Drs. Cynthia and David said...

Thanks for the input. I thought I might put on a little muscle but expected to lose some fat or at least water at the same time, and so was expecting net zero change at first, then a longer term loss again. Instead it's just a big plumpfest. It's not much really, just two lbs, but still, in the wrong direction.

I agree that the weight training doesn't increase appetite particularly, at least the amount I'm doing. There is less running and other cardio, so overall less expenditure. Maybe I'm eating too much- I just don't need many calories unless I'm really active.

I miss oatmeal sometimes too. I eat it once in a while, like you, when I know it will be used soon!

thanks again!

Cynthia

Methuselah said...

Cynthia - one way to judge muscle gain is to assume a correlation with strength. If you are getting stronger, you are gaining muscle. I will let you know if I go on an oatmeal binge. Good luck!