Your power meter is lying to you

When I say lying, it’s really error by omission or perhaps not telling the full story. Power meters are a brutal but vital tool to measure intensity and, provided the data is interpreted and implemented correctly, are very effective when used with structured training. One of the pieces of data it produces incidentally to power is an accurate calorie burn. For any length or intensity of ride, it will calculate how much energy has been expended measured in Kcals.

However, for those of us who use the exercise and diet approach to either maintaining or losing weight, there is a catch. It’s called the Energy Compensation Effect (Careau et al, 2021). Fundamentally it means if the power meter says 1200 Kcals have been burned on the Sunday ride, the consumption of 1200Kcals worth of apple pie and custard after lunch would result in a calorie surplus of 350 Kcals.

I know right, it sucks.

The evidence shows as a result of the activity involved whilst training aerobically, there’ll be less background activity after it. Less fiddling around, walking, more sitting and more sitting stiller. This reduces the effective calorie consumption to about 72%, reducing the 1200 Kcal expenditure during the ride to about 850 Kcals in apple pie and custard terms.

That'd go back...

​Hands up, this was new to me. I was alighted to it by Steve Keane a strength coach (Steve Kraft Coaching on Instagram) who, if you want some science backed (and funny) insights into strength training is really worth a follow. However, it means my simple ‘if I burn off 3500kcals cycling every week, that’s a pound of fat gone’ is, sadly, wrong. I’d need to burn more like 4800Kcals and maintain my calorie consumption at my basal rate. Bugger.

Explains a lot.
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So, if (and only if) you want to lose weight whilst training on the bike this is a metric worth knowing. Perhaps more importantly, it reinforces the point that whilst diet and exercise are important, in fat loss terms, it’s the consumption part of the equation that’s likely to carry greater… er, weight.
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​I’ll write about something happier next time, promise. 

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Rich Smith is a psychology graduate and a British Cycling qualified Level 3 Road and TT coach supporting riders nationally and internationally and is coach to the Great Britain Transplant Cycling team. He loves apple pie and custard. He launched RideFast Coaching in 2015 to deliver one to one, rider centred training that is physiologically effective but also psychologically sustainable.