Eating calories in vs out

[matthew]

So...according to RW "You'll burn roughly 400 to 600 calories per hour during your run, but your body can absorb only 240 to 280 calories per hour "

Does this mean consuming more calories per hour is pointless? Or does a greater calorie intake increase the chances of your body taking in the maximum number of calories?

Clarification? anyone?

[Travs]

I'm no scientist... but in a hard short/medium Fell Race I'm fairly confident I'm burning more than 600 calories per hour, at maximum effort I reckon it's 1000+.... Even in a longer AL I reckon it's still 700+ calories/hour... And I certainly wouldn't want to be cramming 280 calories an hour into me during a race!

[Mike T]

So...according to RW "You'll burn roughly 400 to 600 calories per hour during your run, but your body can absorb only 240 to 280 calories per hour "

Does this mean consuming more calories per hour is pointless? Or does a greater calorie intake increase the chances of your body taking in the maximum number of calories?

Clarification? anyone?

If you try to take in more than your limit it will just sit there and eventually come back, or threaten to do so. Some foods, even if not taken in caloric excess, will do the same - you need to find out through trial and error what you can take and how much of it. Of course if the event is not that long you can rely on your glycogen stores backed up with fat burning - for a road marathon the average person uses roughly half of each - more carbs at the start, more fat at the finish. I rarely eat during the shorter ALs, but Ennerdale and Wasdale are different, and I feel the need for extra fuel after halfway. You can run yourself into hypoglycaemia - low blood sugar - which is no fun, and in itself can cause nausea/vomiting.

[Graham Breeze]

If you try to take in more than your limit it will just sit there and eventually come back, or threaten to do so. Some foods, even if not taken in caloric excess, will do the same - you need to find out through trial and error what you can take and how much of it. Of course if the event is not that long you can rely on your glycogen stores backed up with fat burning - for a road marathon the average person uses roughly half of each - more carbs at the start, more fat at the finish. I rarely eat during the shorter ALs, but Ennerdale and Wasdale are different, and I feel the need for extra fuel after halfway. You can run yourself into hypoglycaemia - low blood sugar - which is no fun, and in itself can cause nausea/vomiting.

From memory a 60 ml SIS Gel contains around 75 cals and even SIS don't recommend you try and absorb 4 gels/hour - and for me carrying the weight of 20+ gels at the start of Wasdale might be slightly counterproductive!

[Travs]

Yes, certainly Wasdale, Buttermere and Ennerdale are races where i'd prefer to take just a little 'proper food' with me, instead of relying on water and gels/dextrose tablets.

Rule of thumb for me is anything likely to take over 5-6 hours and i'll take a little food as backup (over and above emergency food of course). Anything below that and i'll see it through without.

[Hank]

Carl Bell on Twitter yesterday posted about the possibility of trying a BGR: not at the moment because he never runs for more than 4 hours and never eats or drinks when running. Incredible to think he won Buttermere with zero intake of food or liquid.

[Graham Breeze]

From memory a 60 ml SIS Gel contains around 75 cals (**) and even SIS don't recommend you try and absorb 4 gels/hour - and for me carrying the weight of 20+ gels at the start of Wasdale might be slightly counterproductive!

** 87 actually on my box and SIS recommend taking "up to 3/hour" when taking exercise so that's 260- ish cals intake per hour, but at some £ cost!

[Travs]

** 87 actually on my box and SIS recommend taking "up to 3/hour" when taking exercise so that's 260- ish cals intake per hour, but at some £ cost!

Yes i saw that and certainly don't fancy necking that much gel...!

If i needed anything like that much intake then i'd be looking at real food as the first option.

[matthew]

Thanks for the feedback. I'm coming at it from a mountain marathon point of view, where calorie replenishment is needed due to distance and to protect energy stores for the next day.

I find one gel is more than enough.