Calories and cycling
07-26-21, 11:27 AM
#101
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As a reminder, dietary calories are measured in units of energy. The dietary “calorie” is actually a kilocalorie for use in comparison with SI units of work, such as joules or kilojoules. one calorie = 4.184 Joules so one dietary calorie = one kilocalorie = 4.184 kJ.
As you will see in examples below, riders tend to be about 25% efficient at turning dietary calories consumed into useful pedaling work which would be measured again in units of energy. Most of the rest is ultimately dissipated as heat though there is also internal work done just moving the mass of legs, pedals and cranks at a particular cadence.
Power meters measure the instantaneous rate at which external work is being done on the pedals and is measured in Watts= Joules/sec.
For those interested, that internal power load and resulting internal work is strongly dependent on cadence, so at a given speed on the road (and external power load) the total load your body must power will be a higher level that is an increasing function of cadence.
So I presume that’s looking at pedaling at 200W for one hour. Total external work would be 200 J/ sec times 3600 sec = 720,000 J or 720 kJ. At 25% efficiency, that requires 4 x 720 kJ = 2,880 kJ of dietary energy consumed which is 2.880 kJ/ 4.184 kJ/kcal = 688 kcal = 688 dietary calories. The 25% figure is rough and varies a bit with individuals so don’t read more than two figures at most. Figure 700 dietary calories roughly.
Power is actually the rate at which work is being done, measured in watts or kW. Coincidentally, the factor of 4 from the 25% metabolic efficiency roughly cancels the 4.184 conversion factor of dietary calories or kcal to kJ. So, yes, one kJ of cycling work is roughly one dietary calorie consumed.
Probably more than folks wanted to see but there it is for folks who might wonder.
Otto
As you will see in examples below, riders tend to be about 25% efficient at turning dietary calories consumed into useful pedaling work which would be measured again in units of energy. Most of the rest is ultimately dissipated as heat though there is also internal work done just moving the mass of legs, pedals and cranks at a particular cadence.
Power meters measure the instantaneous rate at which external work is being done on the pedals and is measured in Watts= Joules/sec.
For those interested, that internal power load and resulting internal work is strongly dependent on cadence, so at a given speed on the road (and external power load) the total load your body must power will be a higher level that is an increasing function of cadence.
So I presume that’s looking at pedaling at 200W for one hour. Total external work would be 200 J/ sec times 3600 sec = 720,000 J or 720 kJ. At 25% efficiency, that requires 4 x 720 kJ = 2,880 kJ of dietary energy consumed which is 2.880 kJ/ 4.184 kJ/kcal = 688 kcal = 688 dietary calories. The 25% figure is rough and varies a bit with individuals so don’t read more than two figures at most. Figure 700 dietary calories roughly.
Power is actually the rate at which work is being done, measured in watts or kW. Coincidentally, the factor of 4 from the 25% metabolic efficiency roughly cancels the 4.184 conversion factor of dietary calories or kcal to kJ. So, yes, one kJ of cycling work is roughly one dietary calorie consumed.
Probably more than folks wanted to see but there it is for folks who might wonder.
Otto
1.) how many wats does it take to ride 15mph on a road bike?
2.) how many watts does it take to ride 15mph on a hybrid fitness bike?
07-26-21, 11:38 AM
#102
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And to the above post about "how many watts does it take to ride 15 mph?". That's an unanswerable question if we don't know other parameters. But a randomly selection of road bikes should, on average, take fewer watts than a random selection of hybrid bikes.
Last edited by guachi; 07-26-21 at 11:45 AM.
07-26-21, 11:48 AM
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What worked for me was using a free app (LoseIt) to log what I ate and keeping the weekly average calories in at what would maintain my goal weight - and NOT logging exercise for anything less than a 2 hour ride. I've maintained most of that loss for over 10 years now, only have to go back to logging everything a few times like after particular food-filled holiday season or when I had rotator cuff surgery and my exercise went to near zero for a while.
What worked for me was using a free app (LoseIt) to log what I ate and keeping the weekly average calories in at what would maintain my goal weight - and NOT logging exercise for anything less than a 2 hour ride. I've maintained most of that loss for over 10 years now, only have to go back to logging everything a few times like after particular food-filled holiday season or when I had rotator cuff surgery and my exercise went to near zero for a while.
You can manage what you don't measure.
07-26-21, 11:59 AM
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Two things I've always heard. To lose weight, "Eat less and exercise." One could turn that around. The other is "Eat to ride and ride to eat." My caveat, just don't gorge yourself. However there are other factors like metabolism. For that, consulting a sports doctor or nutritionist could be helpful.
07-26-21, 12:20 PM
#105
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From: https://www.sheldonbrown.com/rinard/aero/formulas.html
Otto
Last edited by ofajen; 07-26-21 at 12:24 PM.
07-26-21, 12:38 PM
#106
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It is really difficult to eat less calories for me, i feel sooo low in energy, and worst of all , l get low sugar symptoms (light headed, dizzy, sometimes the sweats), after doctors testing, they said i'm generally healthy
I personally don't think eating less calories will be option for me, all thought it is most effective
18 years ago, i had gone from 250 to 180, by cutting lot of calories, and maintained around 195-200 until i was 34-35, , at which point i started gaining, from 195 to 230, however bc i get the symptoms i described, it is hard to lose weight by calories cutting.
I literally, just naturally eat more, when i gained my weight, albiet, they are healthy choices, its kind of strange.
I personally don't think eating less calories will be option for me, all thought it is most effective
18 years ago, i had gone from 250 to 180, by cutting lot of calories, and maintained around 195-200 until i was 34-35, , at which point i started gaining, from 195 to 230, however bc i get the symptoms i described, it is hard to lose weight by calories cutting.
I literally, just naturally eat more, when i gained my weight, albiet, they are healthy choices, its kind of strange.
If you don't reduce your calorie intake, you will likely not be able to maintain your weight loss. it takes few calories to maintain a 180 pound body, than a 250 pound body. If you continue to eat like a 250# person, you will regain what you lose, all things considered equal.
07-26-21, 12:45 PM
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07-26-21, 02:10 PM
#108
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Too many factors go into determining watts and speed. I raced in a criterium on Saturday and my power was 270w with an average speed of 26mph, if I were to do that solo it would be like 23ish maybe depending in terrain.
And to connect the effort back to calories, the 50min race gave me a calorie burn of 762, so again, a decent ballpark for someone who is relatively novice is likely to be 200-400 calories an hour
And to connect the effort back to calories, the 50min race gave me a calorie burn of 762, so again, a decent ballpark for someone who is relatively novice is likely to be 200-400 calories an hour
07-26-21, 02:17 PM
#109
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Everyone is different, but basically we eat too much.
I've never been heavy or sedentary, max 160lbs at 5'-10" and cycling since 1990. However, when I totally adjusted my lifestyle which included "very little" food, I dropped down to sub 140lbs. "Diet" is not a list of fad foods, its a view on nutrition. I then got married and lost some control over what and when I eat so now up to 150, still lighter than before my "adjustment."
Exercise, such as cycling tones muscles and makes people look nicer.
I've never been heavy or sedentary, max 160lbs at 5'-10" and cycling since 1990. However, when I totally adjusted my lifestyle which included "very little" food, I dropped down to sub 140lbs. "Diet" is not a list of fad foods, its a view on nutrition. I then got married and lost some control over what and when I eat so now up to 150, still lighter than before my "adjustment."
Exercise, such as cycling tones muscles and makes people look nicer.
Lifestyle is about managing all how your body gets nutrition, burns off the calories and stays healthy overall. Over the past 13 years or so (and mostly in the early part of it) I went from ~175 to 205 lbs(!) the heaviest I had ever weighed in my life. I'm (or used to be before age-related shrinkage 
5'-10"+. I'm not stocky so 205 put me into the "obese" category of BMI, a place I could never imagine myself being. I had been eating "OK" but apparently my metabolism was changing.I've always been fairly active: competitive volleyball, hiking, backpacking, skiing, coaching kids' basketball, etc. so I've always been fairly trim...until. I kept worrying about my weight, tried to eat better and took up cycling as an exercise after I developed sciatic nerve issues playing V-Ball
(For those who have never had it, the pain can be excruciating and debilitating Over a year ago I started getting back to sports since my sciatic issues finally went away (whole other story). Got a new pair of hiking boots and started getting back into hiking with an eye back into backpacking (depending on what's left of the Sierra when I get to that point
increased my biking distance and number of days/week. I then started watching my eating even more. Cut down on processed sugar (haven't had any soda in decades and got away from bottled juices), minimized fat intake (tho, we all need a minimum amount of fat to facilitate digestion), focused more on fruits and vegetables, less red meat, and so on.The result was, beginning near the start of this year, I finally noticed my weight was shifting downward. A few pounds every few days or so and then a plateau. And then the weight has continued to drop much more subtly. I have reached the point where I'm less than 10 lbs. (~6-7 lbs.) from where I was 10-15 years ago, something I never thought possible. I am able to wear shorts that I haven't worn in nearly 20 years....and I never thought I would ever be able to get to that point, even 4-5 years ago.
So, tl;dr....diet and exercise are key, no doubt about it. You can do one without the other and notice *some* progress but the missing ingredient is the mental: focus and commitment. Focus is to really understand what one is trying to do..and that should be about changing "lifestyle", not specifically about losing weight. The difference is that if you only diet, you'll be back to dieting again and again. If you change your lifestyle, you only have to do that once. Commitment is staying the course, believing what one is doing is the right path and will get you where you want to be (if it's not the right path, find the path that is right).
I changed my diet and changed my exercise, not necessarily at the same times. However, once I became focused and committed (which was early last year) I watched the results and it blew my mind.
Don't think in terms of only eating less or exercising more. Those are only individual trees. Think in terms of the forest and you will be amazed at what you can accomplish..
Cheers.....
07-26-21, 02:20 PM
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I apologize I have not read everybody's response but wanted to add something to the discussion that may prove beneficial. I have been riding for a few years now and met riders that said they lost x amount of weight since they took up riding. I think that is awesome. What I found with myself was that I was having a hard time explaining how I could not correlate my body weight to the calories my powermeter or even rule of thumb calculations said I burned. I was doing numerous long rides from 100-150 miles on the weekends when I was avidly training and racing with usually another 70 miles during the week usually doing some sort of interval type training rides. My confusion was that in no way was I taking in enough calories to sustain those rides and my metabolism. I just could not figure out how it was possible to do that much work and not be losing some serious weight. On long rides(over 60 miles) I might carry a sleeve of energy chews which was 160 calories and one bottle with a carb/water blend of another 70 calories. On shorter rides I would just have the carb/water blend but just water if it was less than 30 miles.
Last week I was listening to a podcast and it was an interview with Herman Pontzer from Duke University who did some remarkable research that in short says to lose weight exercise is not the solution. What was remarkable is his study showed that a sedentary person burned about the same amount of calories as active persons. Hard to believe but it explains why I was not wasting away for lack of food. Please check it out I could not post a link, just do a search for "Herman Pontzer", Duke, and diet.
Last week I was listening to a podcast and it was an interview with Herman Pontzer from Duke University who did some remarkable research that in short says to lose weight exercise is not the solution. What was remarkable is his study showed that a sedentary person burned about the same amount of calories as active persons. Hard to believe but it explains why I was not wasting away for lack of food. Please check it out I could not post a link, just do a search for "Herman Pontzer", Duke, and diet.
07-26-21, 03:32 PM
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When calculating calories based on power meter data, no - conventional wisdom has it that cyclists don't actually differ all that much (the range last I looked at studies - admittedly with trained cyclists - was about is +- 10%) when it comes to turning calories into watts. Of course your basal metabolic rate differs based on age, sex, weight, height and so on but taking that into account is a bit iffy - you'd have expended (a good part of) that anyway just being alive.
Generally, 200W (which on a road bike on flat terrain with no wind is good for about 31-35 km/hr depending on how aerodynamic you are and how efficient the bike is) requires about 720 kcal plus whatever your basic metabolic rate is (which depends on weight, sex, etc) comes out to let's say about 800 to get a nice round number, so 430 kcal for going hard for half a hour is entirely feasible (or more, or less).
As long as you're watchful what and how much of it you put in your mouth, cycling is going to help.
Generally, 200W (which on a road bike on flat terrain with no wind is good for about 31-35 km/hr depending on how aerodynamic you are and how efficient the bike is) requires about 720 kcal plus whatever your basic metabolic rate is (which depends on weight, sex, etc) comes out to let's say about 800 to get a nice round number, so 430 kcal for going hard for half a hour is entirely feasible (or more, or less).
As long as you're watchful what and how much of it you put in your mouth, cycling is going to help.
YMMV :-)
All that said, I'm guessing most burn fewer calories than those calculated to drive an engine at 200W
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07-26-21, 04:08 PM
#112
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Of course, I'm a SLF (Svelte Lithe Fellow). One of my ride buddies weighs 50% more and puts out 300W to stay with me on climbs. He kills me when the road is flat.
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07-26-21, 05:05 PM
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Doubt many here can actually maintain 200W nonstop for 30 minutes. Measured with a power meter, that is very difficult for an "average or better" rider. I'm not saying there's not riders in this forum who are that strong, but that's a high number for most of us. Ftp tests are easy to perform, requiring a power meter or smart trainer. Zwift has a few variations. Ftp = your power output you can do for one hour. Some of the tests don't require the full hour and give you a fair estimate.
YMMV :-)
All that said, I'm guessing most burn fewer calories than those calculated to drive an engine at 200W
YMMV :-)
All that said, I'm guessing most burn fewer calories than those calculated to drive an engine at 200W
07-26-21, 05:56 PM
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It is really difficult to eat less calories for me, i feel sooo low in energy, and worst of all , l get low sugar symptoms (light headed, dizzy, sometimes the sweats), after doctors testing, they said i'm generally healthy
I personally don't think eating less calories will be option for me, all thought it is most effective
I personally don't think eating less calories will be option for me, all thought it is most effective
Burning fat helps those sugar-craving feelings and low energy when your calories are down.
I started specifically riding zone 2 in February or so and have noticed huge differences in how I feel in between meals through the day. I also don’t feel starving on long rides anymore.
just an opinion.
07-27-21, 11:26 PM
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But I could also be really, really wrong about my estimation of what others can do.
Now my FTP is close to 300W but I ride 8 hours per week and I'm now 47.
07-28-21, 04:26 AM
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It's not much help for your real world situation, but reducing things to the purest theoretical level, all you need to know to calculate calories burned is your mass and how far you've moved it. Elevation change and wind direction would also play into it, but not your speed of travel or any biological details.
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07-28-21, 04:51 AM
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07-28-21, 04:58 AM
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You really think so? I had an FTP of about 200 on about 90 minutes of biking a week in my early 40s. FTP hit 230 on about 2.5 hours. And I assume most people in this forum ride this much or more and could do 200W for 30 minutes.
But I could also be really, really wrong about my estimation of what others can do.
Now my FTP is close to 300W but I ride 8 hours per week and I'm now 47.
But I could also be really, really wrong about my estimation of what others can do.
Now my FTP is close to 300W but I ride 8 hours per week and I'm now 47.
07-28-21, 05:34 AM
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We older cyclists do not have a good dataset of FTP by age or at least that I could find. There are very generic tables showing VO2 max by age.
200 watts average power in an hour is a pretty decent workout even for a fit old timer and it is probably more than most can do on a regular basis at any age. Even if someone has an FTP of 225 watts, are they going to do every workout at nearly 90% of their hardest aerobic effort?
Some of these online calculators say someone burns 500-600 calories when in fact, they did less than half that while ingesting some comercial sugar water and then getting home and drinking a recovery drink. Gee, I wonder why it is so hard to lose weight.
Here is one simple idea, is it possible to outride a bad diet?
200 watts average power in an hour is a pretty decent workout even for a fit old timer and it is probably more than most can do on a regular basis at any age. Even if someone has an FTP of 225 watts, are they going to do every workout at nearly 90% of their hardest aerobic effort?
Some of these online calculators say someone burns 500-600 calories when in fact, they did less than half that while ingesting some comercial sugar water and then getting home and drinking a recovery drink. Gee, I wonder why it is so hard to lose weight.
Here is one simple idea, is it possible to outride a bad diet?
07-28-21, 06:33 AM
#122
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At the end of the day no matter who you are weight loss is calories in vs calories out. If you are serious about weight loss then accounting for calories has to be recognized. Out training a bad diet is very difficult and you better be young and workout a ton or you don't have a prayer.
There is no simple magic bullet. If you are at least somewhat aware of what you are throwing down you have a better chance than if you eat everything in sight and wonder why your little spin around the block isn't burning the weight off of you.
07-28-21, 06:39 AM
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You really think so? I had an FTP of about 200 on about 90 minutes of biking a week in my early 40s. FTP hit 230 on about 2.5 hours. And I assume most people in this forum ride this much or more and could do 200W for 30 minutes.
But I could also be really, really wrong about my estimation of what others can do.
Now my FTP is close to 300W but I ride 8 hours per week and I'm now 47.
But I could also be really, really wrong about my estimation of what others can do.
Now my FTP is close to 300W but I ride 8 hours per week and I'm now 47.
I said average though, and your #'s label you as a Cat 3 racer, assuming you weigh 150 lbs (as power output is relevant only compared to your weight) That's not average. YMMV :-)
https://datacranker.com/cycling-powe...io-calculator/
07-28-21, 06:47 AM
#124
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That's great, and you're obviously a strong cyclist
I said average though, and your #'s label you as a Cat 3 racer, assuming you weigh 150 lbs (as power output is relevant only compared to your weight) That's not average. YMMV :-)
https://datacranker.com/cycling-powe...io-calculator/
I said average though, and your #'s label you as a Cat 3 racer, assuming you weigh 150 lbs (as power output is relevant only compared to your weight) That's not average. YMMV :-)
https://datacranker.com/cycling-powe...io-calculator/
07-28-21, 06:49 AM
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Okay
How about Cycling Analytics?
"Serious riders"
50% of their users have power of 272 or less.
Again, I said "average" rider.
Users of Cycling Analytics I'd bet are stronger.
Readers of this forum I'd bet are closer to average than the 50th percentile Cycling Analytics user.
You are a strong rider
I stand by my original post. The average reader here has ftp's nowhere near yours.
https://www.cyclinganalytics.com/blog/2018/06/how-does-your-cycling-power-output-compare
How about Cycling Analytics?
"Serious riders"
50% of their users have power of 272 or less.
Again, I said "average" rider.
Users of Cycling Analytics I'd bet are stronger.
Readers of this forum I'd bet are closer to average than the 50th percentile Cycling Analytics user.
You are a strong rider
I stand by my original post. The average reader here has ftp's nowhere near yours.
https://www.cyclinganalytics.com/blog/2018/06/how-does-your-cycling-power-output-compare
Last edited by bfaIllini; 07-28-21 at 07:02 AM.
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