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Five Reasons Your Garmin Might Be Holding You Back from Faster Ride Times.

Coaching Garmin MyFitnessPal Racing Weight Strava Training Weight Loss Weightloss

Guest Blog by James Belbin, nutritionist at Your Nutritional Blueprint

It’s Sunday 11am. And you’re stopping at your local café 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 February.

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 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 apple pie & 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!!

Café stop

Why We Have to Ignore Our Devices for Weight Loss

Now this example might sound a bit clunky and clichéd, but its important to know why some people struggle to shift body fat when the hours on the bike can mount up. 

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.


First let’s look at weight loss and the positive effects on ride times.

If you are looking to improve your times, it usually is a good idea to shift some weight but without losing power or stamina.

The reason: Energy expenditure.

If you watch the Tour De France, you’ll notice that all the riders are stick thin.  The cycling media also shares weight-loss tips diets and advice so it’s simple:

Lose weight to ride faster, right?


I did a quick Google online and found that on a 6% incline its estimated that a rider will typically save 5 watts (or 4 seconds per km) for every kilogram of weight. [1] So it’s easy to see you don’t want to be carrying ballast if you’re 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 staged 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’s sometimes down to the over-estimation of calories burned on the bike during the ride.  MyFitnessPal takes it one 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.  Now, let’s explain the science 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.  

Five reasons why: 

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?

Why calorie counting for fatloss might be holding you back from your goals

image: Why calorie counting for fat loss might be holding you back from your goals.

2. Individuals Burn Calories Uniquely and Variably.

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 number 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 is unaware of the difference win your ability. Adding a power meter or the very least a heart rate strap to measure the specifics of efficiency and power would improve the readings, but not provide exact numbers.

  • 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.

3. What and How Much You Eat Influences How Many Calories You’ll Burn

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.

Why calorie counting for fat loss might be holding you back from your goals

image: Why calorie counting for fat loss might be holding you back from your goals

4. Your Weight History Influences

If you've ever been overweight / obese, your metabolic rate may be lower than equations predict due to something called adaptive thermogenesis. 

Consider a 40-year-old man who weighs 200 pounds. Equations predict he'll require 2,759 calories / day to maintain his weight.

He starts to eat less in an effort to lose weight.

Over time, he loses 20 lb, or 10% of his previous body weight. Since a smaller body needs to process fewer calories to live, his total caloric output goes down.

Because the man has been living on a calorie deficit and lost significant
weight, his brain thinks he’s in danger of starving to death. His fat cells release less leptin, a hormone that influences hunger and activity cues.

This sends the body into calorie conservation mode, causing the man to subconsciously move less (via a drop in non-exercise activity thermogenesis, or NEAT) and making his muscles more efficient so he burns fewer calories even when he exercises.

Because of this adaptive thermogenesis, research shows the man may always require up to 300 fewer calories per day than equations predict to maintain his new weight.

Whereas most equations would predict the man requires 2,623 calories per day to maintain 180 lb, he might actually need as few as 2,323 daily.

5. 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’re not trying to take away any of the fun of comparing data on your rides, competing with your friends, or simply tracking your performance over segments or completed rides, what we ARE saying is don’t take the calorie burn as gospel when trying to match your calorie intake on MyFitnessPal.  Enjoy your cycling as a form of exercise over letting inaccurate data hold you back.

If your goal is weight-loss through cycling, plan for the smallest deficit you can manage to get away with over longer periods to help you create the necessary deficit.

Work with a coach to work out your TDEE which is your total daily energy expenditure and choose a plan to help deliver a small managed deficit to achieve it, they will help you create a manageable plan that includes your training rides plus your non-training days.

A good coach can help you establish good weight loss protocols including periodisation, carbohydrate bunching or loading.

If you want to truly want to lose weight whilst cycling, it’s better to use the winter months, when cycling is less intense to diet your weight down so that you don’t impact your heavier seasonal riding or keep cycling to lower intensity fun sessions where you don’t require the calorie intake to be so high.

If you want more help, James is happy to answer any questions or comments below, or book yourself a free consultation with him via this Link

Please share this post with your cycling club if you think it might help a few of your fellow cyclists

James Belbin is an evidence based nutritionist based in Brighton, East Sussex.  His interest in cycling stretches back to the early 80s when he won a Paul Ricard vintage cycling cap in the school tombola. His fascination with the Renault team of Fignon and LeMond in that year’s Tour de France cemented his love of the sport. He has dreams of one-day taking on the Etape d’Tour.

James works with local and online weight-loss clients, offering a number of packages to suit his client’s goals. His ultimate goal is to reduce the burden of obesity on the population of the UK.

Adapted from Precision Nutrition – Why Calorie counting isn’t great for weight loss > Free Download here.


Reason 1

Burnett CM, Grobe JL. Dietary effects on resting metabolic rate in C57BL/6 mice are differentially detected by indirect (O2/CO2 respirometry) and direct calorimetry. Mol Metab. 2014 Mar 21;3(4):460-4

Ferguson T, Rowlands AV, Olds T, Maher C. The validity of consumer-level, activity monitors in healthy adults worn in free-living conditions: a cross-sectional study. Int J Behav Nutr Phys Act. 2015 Mar 27;12:42.

Lee JM, Kim Y, Welk GJ. Validity of consumer-based physical activity monitors. Med Sci Sports Exerc. 2014 Sep;46(9):1840-8.

Simonson DC, DeFronzo RA. Indirect calorimetry: methodological and interpretative problems. Am J Physiol. 1990 Mar;258(3 Pt 1):E399-412. Review.

Reason 2

Arrizabalaga M, Larrarte E, Margareto J, Maldonado-Martín S, Barrenechea L, Labayen I. Preliminary findings on the influence of FTO rs9939609 and MC4R rs17782313 polymorphisms on resting energy expenditure, leptin and thyrotropin levels in obese non-morbid premenopausal women. J Physiol Biochem. 2014 Mar;70(1):255-62.

Benedict C, Hallschmid M, Lassen A, Mahnke C, Schultes B, Schiöth HB, Born J, Lange T. Acute sleep deprivation reduces energy expenditure in healthy men. Am J Clin Nutr. 2011 Jun;93(6):1229-36.

Bisdee JT, James WP, Shaw MA. Changes in energy expenditure during the menstrual cycle. Br J Nutr. 1989 Mar;61(2):187-99.

Dalgaard K, Landgraf K, Heyne S, Lempradl A, Longinotto J, Gossens K, Ruf M, Orthofer M, Strogantsev R, Selvaraj M, Lu TT, Casas E, Teperino R, Surani MA, Zvetkova I, Rimmington D, Tung YC, Lam B, Larder R, Yeo GS, O’Rahilly S, Vavouri T, Whitelaw E, Penninger JM, Jenuwein T, Cheung CL, Ferguson-Smith AC, Coll AP, Körner A, Pospisilik JA. Trim28 Haploinsufficiency Triggers Bi-stable Epigenetic Obesity. Cell. 2016 Jan 28;164(3):353-64

Davidsen L, Vistisen B, Astrup A. Impact of the menstrual cycle on determinants of energy balance: a putative role in weight loss attempts. Int J Obes (Lond). 2007 Dec;31(12):1777-85. Epub 2007 Aug 7. Review

Dolinoy DC, Weidman JR, Waterland RA, Jirtle RL. Maternal Genistein Alters Coat Color and Protects Avy Mouse Offspring from Obesity by Modifying the Fetal Epigenome. Environmental Health Perspectives. 2006;114(4):567-572

Hubáček JA, Pikhart H, Peasey A, Kubínová R, Bobák M. FTO variant, energy intake, physical activity and basal metabolic rate in Caucasians. The HAPIEE study. Physiol Res. 2011;60(1):175-83.

Kajimura S, Saito M. A New Era in Brown Adipose Tissue Biology: Molecular Control of Brown Fat Development and Energy Homeostasis. Annual review of physiology. 2014;76:225-249.

Waterland RA. Epigenetic mechanisms affecting regulation of energy balance: many questions, few answers. Annu Rev Nutr. 2014;34:337-55.

Wolff GL, Kodell RL, Moore SR, Cooney CA. Maternal epigenetics and methyl supplements affect agouti gene expression in Avy/a mice. FASEB J. 1998 Aug;12(11):949-57.

Reason 3

Glickman N, Mitchell HH, Lambert EH, Keeton RW. The total specific dynamic action of high-protein and high-carbohydrate diets on human subjects. J Nutr. 1948 Jul 10;36(1):41-57.

Hall KD, Heymsfield SB, Kemnitz JW, Klein S, Schoeller DA, Speakman JR. Energy balance and its components: implications for body weight regulation. Am J Clin Nutr. 2012 Apr;95(4):989-94.

Reason 4

Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011 Aug 27;378(9793):826-37.

Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. International journal of obesity (2005). 2010;34(0 1):S47-S55.

St. Pierre., B. (2016). Can Eating Too Little Actually Damage Your Metabolism? Exploring the truths and fallacies of ‘metabolic damage’. Retrieved March 24, 2016, from


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