2

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Cycling 100 miles, fat-adapted.

Answered on August 19, 2014
Created September 20, 2012 at 6:57 PM

According to this calculator I would burn 5,880 calories cycling 100 miles in 9 hours. According to this calculator my basal metabolic rate is 1600 calories. According to this book, max regeneration of energy via beta-oxidation (fat burning) is 2.5 kcal/minute (that's 2.5 calories right?) Which would mean at max, my body can produce 260 calories per hour from body fat.

So put it all together and I will burn through 6480 calories during my 9 hour ride and only 2340 of those calories could come from body fat. So my options are either A) ride at a slower pace (<11/12 mph) or B) consume 4140 calories from food. Am I calculating this right?

B3173217a49b5b0116078775a17eb21d

(11488)

on September 21, 2012
at 07:04 AM

Gluconeogenesis creates glucose at a rate of about 160g/day (more in fat-adapted people, less in sugar burners) which would contribute about 240kcal over the course of a 9 hour ride. About a third of that would be used by the process of gluconeogenesis itself, leaving only about 150kcal for cycling... http://ajcn.nutrition.org/content/90/3/519.full

64433a05384cd9717c1aa6bf7e98b661

(15236)

on September 20, 2012
at 09:48 PM

During the few days before you should be resting and eating a reasonable amount of carbs. the day of the ride eat a big protein and fat breakfast (low carb). This should be your best option.

2e5dc29c61f97d335ffb990508424719

on September 20, 2012
at 08:59 PM

fruit of any kind is good, too.

2e5dc29c61f97d335ffb990508424719

on September 20, 2012
at 08:58 PM

Bacon, egg, avocado breakfast. Other than water I generally don't eat during the ride. for 25-40 miles this is no big deal. If you are going 100 miles you will need a meal at some point. If lunch I would suggest lunch meat in lettuce (or kale) wrap, avocado, coconut. Drink either coconut water or green tea.

De641ff2accb4975e1f42886b43009db

(2227)

on September 20, 2012
at 08:19 PM

How do you fuel your rides?

De641ff2accb4975e1f42886b43009db

(2227)

on September 20, 2012
at 07:59 PM

You're right, that is slow. I'll be riding this with one other person, so drafting won't be as beneficial as it would be in a group. I'm just trying figure out the best way to approach this ride. Thanks for your answer.

06ca9c524c28bc3fba95d4d90f8f43c6

on September 20, 2012
at 07:54 PM

+1 Great answer all the way around. Thats very slow, even for a hypothetical bike ride :) or there is a 100 mile high mountain somewhere that I'm not aware of.

64433a05384cd9717c1aa6bf7e98b661

(15236)

on September 20, 2012
at 07:47 PM

Yes, use fat to make ATP. If you're riding with other people you should be able to average closer to 15 at least. Also, you should get some tailwinds and descents to help the pace. Where are you riding? Or is this a hypothetical 100 miles?

De641ff2accb4975e1f42886b43009db

(2227)

on September 20, 2012
at 07:23 PM

When you say "burn fat" you mean "produce energy" right? Also, 9 hours is averaging 11 MPH, which is fairly slow.. but even maintaining 13 MPH is a 7.6 hours.. factor in hills and wind that's a tough pace.. IMO.

De641ff2accb4975e1f42886b43009db

(2227)

on September 20, 2012
at 06:57 PM

I know this question isn't strictly related to a paleo diet, but I want to know how this would work in a fat-burning state and that is pretty paleo right?

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4 Answers

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3
64433a05384cd9717c1aa6bf7e98b661

(15236)

on September 20, 2012
at 07:17 PM

You can't calculate that because people burn fat at different rates. Another way of saying that is that people can burn fat up into different heart rate ranges.

100 miles probably shouldn't take 9hrs either.

64433a05384cd9717c1aa6bf7e98b661

(15236)

on September 20, 2012
at 07:47 PM

Yes, use fat to make ATP. If you're riding with other people you should be able to average closer to 15 at least. Also, you should get some tailwinds and descents to help the pace. Where are you riding? Or is this a hypothetical 100 miles?

06ca9c524c28bc3fba95d4d90f8f43c6

on September 20, 2012
at 07:54 PM

+1 Great answer all the way around. Thats very slow, even for a hypothetical bike ride :) or there is a 100 mile high mountain somewhere that I'm not aware of.

De641ff2accb4975e1f42886b43009db

(2227)

on September 20, 2012
at 07:23 PM

When you say "burn fat" you mean "produce energy" right? Also, 9 hours is averaging 11 MPH, which is fairly slow.. but even maintaining 13 MPH is a 7.6 hours.. factor in hills and wind that's a tough pace.. IMO.

De641ff2accb4975e1f42886b43009db

(2227)

on September 20, 2012
at 07:59 PM

You're right, that is slow. I'll be riding this with one other person, so drafting won't be as beneficial as it would be in a group. I'm just trying figure out the best way to approach this ride. Thanks for your answer.

64433a05384cd9717c1aa6bf7e98b661

(15236)

on September 20, 2012
at 09:48 PM

During the few days before you should be resting and eating a reasonable amount of carbs. the day of the ride eat a big protein and fat breakfast (low carb). This should be your best option.

3
B3173217a49b5b0116078775a17eb21d

(11488)

on September 20, 2012
at 08:22 PM

Well, even at lower intensities you burn muscle glycogen too.

In the (brilliant) Lore of Running, Tim Noakes says: "Untrained subjects eating a normal diet store about 280g of carbohydrate in their muscles (Hultman 1967; Blom, Costill et al 1987), wherase values of up to 720g are usually found in trained athletes who have not exercised for 24 to 48 hours and who have allowed their muscles sufficient time to fill up their carbohydrate stores completely (Costill, Sherman, et al 1981)."

So if you are able to cycle 100 miles you must be resonably fit, so we'll say that you have 600g of glycogen that you could potentially access too (=2400 kcal).

This reference has a maximum beta-oxidisation rate of 0.6g/min = 324kcal/hour (although this depends on the exercise and the person).

(5880-2400kcal)/9hours = 377 kcal/hour, so you'd need to find another 50kcal/hour from food.

It would be a but silly to try and cycle for 9 hours fasted. Even the "low-carb" endurance runners take on some carbohydrates to replenish their depleted glycogen stores.

3
2e5dc29c61f97d335ffb990508424719

on September 20, 2012
at 08:06 PM

I ride recreationaly (Not racing anymore). I have not ridden that far in a long time. Most of the the rides are in the 25-40 mile range. We average 12-15 MPH depending on conditions. I agree with above that 11 MPH seems on the slow side. We generally don't stop and I am never tired. Doubling or tripling would not change that. Not sure about your math but I don't think you have to worry about bonkng. 100 miles is doable in a day on a bike as long as there are no strong headwinds. (bonking = cycling term for running out of energy,what runners call "hitting the wall")

2e5dc29c61f97d335ffb990508424719

on September 20, 2012
at 08:58 PM

Bacon, egg, avocado breakfast. Other than water I generally don't eat during the ride. for 25-40 miles this is no big deal. If you are going 100 miles you will need a meal at some point. If lunch I would suggest lunch meat in lettuce (or kale) wrap, avocado, coconut. Drink either coconut water or green tea.

De641ff2accb4975e1f42886b43009db

(2227)

on September 20, 2012
at 08:19 PM

How do you fuel your rides?

2e5dc29c61f97d335ffb990508424719

on September 20, 2012
at 08:59 PM

fruit of any kind is good, too.

1
3ce6a0d24be025e2f2af534545bdd1d7

(26217)

on September 21, 2012
at 01:35 AM

you are also forgetting about gluconeogenesis where your body can create glucose from glycerol, lactate, or alanine. Also, becoming fat adapted, your body makes dramatic adaptations that reduce the need for glucose energy which, in turn, increases your ability to burn fat.

I've done centuries staying between 4-5 minutes per mile with only two bananas and two power bars and water (this was pre-primal, pre-fat adaptation). So it definitely can be done.

B3173217a49b5b0116078775a17eb21d

(11488)

on September 21, 2012
at 07:04 AM

Gluconeogenesis creates glucose at a rate of about 160g/day (more in fat-adapted people, less in sugar burners) which would contribute about 240kcal over the course of a 9 hour ride. About a third of that would be used by the process of gluconeogenesis itself, leaving only about 150kcal for cycling... http://ajcn.nutrition.org/content/90/3/519.full

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