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Daily weight fluctuations… or "I sh!t a pound"!

I’m currently monitoring my weight, and more importantly my fat percentage, to see how quickly a low fat diet has an effect – blog post on that to come later.

As part of weighing myself every week I wondered how much variation there was in the figures and therefore could I really tell if I’d had a good or bad week?

So as a little mini-experiment I weighed myself every hour or so throughout one day to see how much the measurements fluctuated – and here’s the graphs.

daily weight fluctation

daily fat percentage fluctations

You can see that my weight rises throughout the day with spikes after lunch and dinner, and conversely my fat percentage drops throughout the day – with corresponding troughs after meals.

Which seems to make sense to me - eating a good meal doesn’t immediately convert it into fat and so the fat percentage is temporarily lowered – but you’re back where you started the next morning.


Through-out the day, although it was random variations, my weight varied plus or minus 0.5kg (+/- 0.4% fat). And I guess this amount of variation should be no surprise as even a small glass of water weighs 0.1kg.

So for anybody watching their weight anything less than this shouldn’t be considered a success – as Peter Kay famously said in his stand-up routine on Slimming World – “I shit a pound!

Scales Accuracy

I also did a micro-experiment within the mini experiment as I wanted to see how much the fluctuations were due to the accuracy of the bathroom scales (OMRON BF508 Body Composition Monitor).

Taking 3 measurements immediately after each other, and without moving the scales in case floor position has an effect, they showed a variation of +/- 0.1kg (+/- 0.2% fat) which seems as good as you’re going to get for a consumer product.

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Founder of Live Forever Club. Author of the Live Forever Manual.

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