"Then my body died. I've analysed my food wrappings and calculated I ate less than 5,000 calories the entire time I was out!" from his account on Ukclimbing.com
Isn't analysing calorific requirement something he should have been doing before setting off???
Assuming he's working at around 700 calories per hour, total requirement x 24 hrs = 17,000 calories, which would be 59 Mars bars (284cals for 65g bar) or 3.8 kilos weight!
Clearly he wouldn't carry that weight, but higher calorie, lower weight food to a lower calorific total of, say around 10,000-12,000 calories should go a long way to preventing him feeling "'bonked' for the last 2/3 of the round."
NB: the 700 calories per hour is just phyical exhertion of climbing hills quickly on rough terrain and takes no account of body keeping itself warm in sub zero termperatures - add another 100-200 cals per hour for this.
Carrying around 2-2.5kg of high-energy foods is a necessary evil, although admitedly not as quote-worthy as hallucinations and the like.
Anyway, little wonder he's so confident of doing it again in under 24 hrs - probably as much credit to my pocket calulator as to his legs when he finally does.