After all the training – the countless hours in the gym or on a bike, pushing their bodies to the limit – the last step for Saunders and L'Herpiniere in their physical preparation was . . . to put on fat. Seriously. The rigors of the journey will drain all the stores and so the goal is to add a surplus. "Even though we'll be eating about 6,000 calories a day, there's an extraordinary metabolic turnover in terms of energy," Saunders says.

For Saunders, the process of adding weight was as simple as eating the type of junk food well-conditioned athletes usually avoid ("we've just been getting donuts, and steak, and bacon, and barbecue – everything!"). But trying to pack on 25 pounds of fat while enduring top-level, intense conditioning is actually hard. If everything goes as planned, Saunders calculates that all his work packing on the pounds will pay off. "We'll lose about two to three pounds a week. I'll come back kind of underweight, but not dangerously so."