How many kilowatt hours have I burnt losing weight? Not that many

English: inner workings of the magnetic resist...
English: inner workings of the magnetic resistance bicycle (Photo credit: Wikipedia)

Here’s a slightly sobering calculation – both in terms of what it tells us about human energy use and human frailty.

Since I started working in the gym, about 18 months ago, I think I have lost about 40 lbs of fat (weight loss is a bit more than that, but I am concentrating on fat).

If human fat has a calorific value of about 4000 kilocalories per pound, this all works out at about 44 kilowatt hours – around £5 ($7 or so) worth of electric power. (Or, judging by the winter gas bill I have just received this is around a day’s worth of gas usage).

Thinking of it another way – 100 watts on the exercise bike is fairly easy to maintain for a sustained period (I would not normally do more than half an hour on this but I am sure I could do this for several hours if all else fails) – this 444 hours.

Of course I have used far more than this to sustain this weight loss – but it puts our routine energy use into perspective to think that all that effort is just a day’s worth of hot water, hobs and central heating.