I have been searching the net for some solid numbers and formulas so that I carry the proper amount of nutrition during longer rides (40+ miles). So far I found one decent site and the rest were either too vague or were selling products.

What I am looking for is:

1. What is the starting amount of calories that the body usually hold in glycogen and blood sugar?
2. At what point is the body store considered depleted and you hit "bonk" or as other describe it, the wall?
3. How much fat and protein can the body convert to energy per hour?
4. After consumption of carbs, proteins and fats during a ride, how long does it take before it hits the blood steam?


I know that roughly I burn about 500 calories per ten miles on my rides. I'm not going to debate this number and I will ignore anyone that does. 2000 calories burned at 200# in 40 miles road cycling with hills, wind, a stop every 5 miles for traffic lights/regroups etc is certainly reasonable (if not on the low end) than using some formula that some nitwit uses at a velodrome.

What I have found so far is this site:
https://www.momsteam.com/nutrition/en...sked-questions

According to that site, I would need to consume 2160 (360 * 6 hours) calories during a century. I have heard various people say that the body stores about 1800 calories in blood sugar and muscle glycogen. 1800 + 2200 (rounded) = 4000 calories of the 5000 I will burn during a century. Does that mean my body is converting 1000 calories of body fat into energy?

Does anyone have any good links with numbers and formulas?

Roughly 2000

You 'bonk' when your blood sugar gets low. Your muscle, liver and blood stores of glycogen don't deplete at the same rate.

You won't be converting much protein but you should be able to get a little over 300 Cals/hr from fat stores. How much fat you burn is individual and depends on your fitness and the intensity you're riding at.

The only food source that will provides any useful energy is carbs and they should be digested in 30min or so depending on the type and glycemic index of the food eaten.


That's a good description. For more detailed info you should buy her book, "Sports Nutrition Guidebook".

That's about the maximum amount of carbs your body will be able to assimilate. You would need to experiment and see if it works for you.

That's correct. More likely you'll get about 1800 cals from fat. You may not like to hear it but if you're taking 6 hrs to complete a century you won't be burning 5000 Cals unless it's all uphill. 5000 Cals in 6 hrs corresponds to about 235 watts which should easily get you a 5 hr century unless you're carrying a parachute.

The site you quoted above is accurate. It's best to just experiment on some longer rides and see how you feel. As your fitness improves (and your weight drops) you'll be able to extract a greater % of your energy from fat stores.

Formulas are pretty much useless for this. You can't replenish during the ride what you burn during the ride- you will get sick. So you need to learn how much you can eat. 250 cal/hr is a good start for most people. It'll change with changing conditions- heat and dehydration both make it easier to feel ill.

The more trained you are the better you get at burning fat. That means it takes longer to bonk. You bonk because while the body can run on fat, albeit at a lower power output, the brain only runs on glycogen. When your blood sugar runs low you get slow and stupid. It won't hurt you but it's not pleasant. If you do it enough times you will learn to recognize when the bonk is coming on and will be better able to function while bonked.

https://www.hammernutrition.com/
They have exactly what you requested. Plus more.

Thank you for the replies. I have a better idea of what is going on and a better direction go. I will be doing a lot more reading and buying a book or two.