quote:

Ranulph Fiennes made a two-person unsupported 1,600-mile crossing of Antarctica in 1992 and 1993. Careful measurements of energy consumption using isotope-labeled water showed that they were burning an astounding 7,000 calories a day for 96 days. During one ten-day period while they ascended the plateau, they averaged 11,000 calories a day. Even though they were eating 5,000 calories a day, they lost 48 and 54 pounds respectively during the trip.