It’s Sunday 11am. And you are stopping at your local cafe for a well earned coffee and cake.  Your Garmin has auto-paused and says you’ve covered 60km this morning.  Only another 40km to go, homeward bound for your 3rd century ride of the year and it’s only the end of January.
Well done you. You’ve earned that flat white and a blueberry muffin.
You get home, soaking wet, content that you finished in a good time.  You wash the bike, upload your ride to Garmin Connect/Strava and head for the bath.
What do you for dinner your partner shouts?
You’re starving beyond redemption….anything you holler back, “I could eat a horse”!
You glance down at your watch.  It’s telling you that you consumed 5500 calories.  Not bad,  I can allow a little extra for dinner.  Maybe some custard….
…but can you?
I think we all have these experiences after a bike ride.  The physical exertion of a day-long ride followed by the post-ride binge.  We deserve it. And in the majority of cases we can take it on and absorb those calories with ease.  After all, risk and reward, right!!
However if your goal is weight-loss and cycling is your preferred method of achieving it, then sometimes you will need to ignore the watch and your physical hunger cues and try to limit your meals after you finish on the bike.
We need to ignore some of the articles posted by cycling monitor manufacturers on the benefits of recording our calorie intake on a bike. If you are looking to improve your  times, it usually is a good idea to shift some weight in the close season when your intensity is lower.
The reason:- Energy expenditure.
First let me explain. If you watch the Tour De France, you notice that all the riders are stick thin.  The cycling media also shares weightless tips diets and advice so its simple.  Lose weight to ride faster right?
I did a quick google online and found that on 6 per cent incline its estimated that a rider will typically save 5 watts (or 4 seconds per km) for every kilogram of weight. [1]  So its easy to see you don’t want to be carrying ballast if you are riding hills as invariably every club rider is. However professional riders tend to lose their body weight during the close season when training intensity is lower and allow for minor weight loss during stages longer events to gain a power to weight advantage.
Trying to lose weight taking part in long sportive and club rides is for some people harder than it should be.  And that is sometimes down to the over-estimation of calories burned on the bike during the ride.  MyFitness pal takes I once step further by positively encouraging you to eat them back the same day.
But surely cycling allows us to freely cycle without worrying about this stuff, well yes and no.
The problem is that we tend to burn far less than we think we do and the devices are making it worse.  Firstly lets explain the concepts behind calorie burn:
The calorie expenditure figures you see in lifestyle publications, online calculators, and fitness trackers are based on laboratory averages with large margins of error.
Ten reasons why are:-
  1. CALORIE BURN estimates are imprecise
Consumer fitness trackers are off by about 30% for total daily calorie expenditure. And for aerobic exercise, nearly all devices show errors between 9% and 23%. They may be made more accurate by heart rate chest straps and power meters but hands up if you are using them on sportive and training rides?
Takeaway point:- At the very minimum allow for 10% inaccuracy of your device based on the device itself.
Many factors affect the true number of calories you will individually  burn during exercise and at rest.
    • GENES A single variation in the FTO gene can cause you to burn 160 fewer calories per day.
    • BROWN FAT In cold environments, people with brown fat (fat tissue containing more mitochondria) burn up to 400 calories more per day than people without it. Diet is also a factor:  In one study, people who ate capsaicin burned 120 more calories per day via brown fat activation. A hot topic is Wim Hofs Way of the Iceman and there may be more to this than just a passing fad.
    • SLEEP Sleep deprivation for a single night may decrease calories burned by 5-20%.
    • CYCLING EFFICIENCY  A veteran of 10,000 km per year and 15 years of cycling will not burn the same amount of calories as a matched weight rider in his first season of sportive across the same distance.  As you gain experience there will be a level of physical efficiency, fitness and pacing that will offset your calorie expenditure.   Strava will always be aware of the difference without a power meter or the very least a heart rate strap to measure the specifics of efficiency and power.
    • HORMONES Women’s menstrual cycle affects their resting metabolic rate. Overall, it’s not unusual for an individual’s metabolic rate to vary by 100 calories from day to day.
    • EPIGENETICS External factors affect how genes are expressed. In mice, when a mother eats more of a specific nutrient (methyl donors) during pregnancy, her offspring burn 5% more calories per day than others. Human studies indicate the potential for similar findings.
Importantly, you’ll burn more energy digesting some macronutrients than others. Depending on the make up of your meals, will define how many calories you will burn on your ride.
If you’ve ever been overweight / obese, your metabolic rate may be lower than equations predict due to something called adaptive thermogenesis.
  1. Heart Rate monitors and Power Meters.
Without either of these, heart rate zones are less accurate and therefore calorie expenditure will also be less likely to illustrate a true picture of how much energy went into the ride you just completed.
There you go, five reasons, you might not be getting the sort of calorie burn that your cycling device is telling you.
Putting it all together.
  • Calorie burn estimates are imprecise;
  • Individuals burn calories uniquely and variably;
  • What and how much you eat influences the calories you’ll burn; and Your weight history influences how many calories you’ll burn…
  • …trusting your device  may be less reliable than you think.
Obviously we are not trying to take away any of the fun of comparing data on your rides, competing with your friends, what we are saying is don’t take the calorie burn as gospel when trying to match your calorie intake on Myfitnesspal.  If you want to truly lose weight whilst cycling, its better to use the close season with less intensity to diet your weight down so that you don’t impact your heavier seasonal riding.
If you want more help, James is happy to take on comments below, or book yourself a free consultation with him via this Link.
Please share this post with your cycling club.
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