Health Quantified Self Sport

What I learnt from tracking my body fat % every day for 6 months

That’s not me, that’s 50 Cent.

50 Cent likes Vitamin Water. He invested in the company early on and regularly advertises its products.

50 Cent is in good shape, so Vitamin Water must be good for you.

But then… Vitamin Water also contains a remarkable amount of sugar: almost 4 teaspoons per bottle.

So is it healthy (vitamins! water!) or not? And what about other foods? What are the factors that make a real difference to health?

I felt confused by conflicting messages about diet and exercise. So decided to measure it for myself, by tracking my body fat % every day for six months.

Why body fat %?

I figured this would be a good way to capture the effect of both inputs (food/drink) and outputs (exercise). I assume that the body fat % is a net result of those two.

Also, I thought that whatever I saw in the data should be reinforced by visible changes when I looked in the mirror:

Poor guy who went through that before/after photoshoot.

What happened to me?

Headline news: my body fat % went down :)

  • My fat % went down for the first three months, then stabilised
  • Two possible reasons why it stabilised:
    • After three months my daughter was born (less sleep, slightly less healthy eating, slightly less exercise)
    • It took a little while to burn off the excesses of Christmas
  • Fat takes 1-2 days to form in your body (even after a pizza party, the effects would not show up in my body fat % for 24-48 hours)

What did I conclude?

  • You manage what you measure – i.e. the simple act of writing down the numbers influences your choices about what you eat and how often you exercise
  • Tracking this stuff is very easy now (much easier in fact than they way I did it, with a combination of Tanita scales and Evernote – there are devices/apps that record all this automagically)
  • The impacts of bad food/booze and exercise were exactly as I suspected. Bad food/booze = more fat, exercise = less fat (duh!)
  • Pizza is still delicious, no matter what you do…


If you’re interested in self-tracking, jump to the posts on tracking money and running.

For more miscellaneous musings, follow @toddmgreen on Twitter or sign up for emails.

Cheers ~ Todd