Eating the calorie equivalent of 15 burgers a day is hardly what you'd call a fitness regime, but it's just the ticket before a gruelling polar adventure.
Justin Jones, 28, and James Castrission, 29, have each put on about 20kg in preparation for their 2200km trek across Antarctica, to the South Pole and back.
A century after Norwegian adventurer Roald Amundsen reached the Pole, the Sydney schoolmates are hoping to score a first, repeating the feat but this time without a support crew or husky dogs. Three previous expeditions without support have failed.
The pair aren't strangers to expedition milestones - in 2008 they were the first to kayak 3300km across the Tasman to New Zealand.
Yesterday, the men farewelled their families and friends at Sydney International Airport as they prepared to traverse some of the world's windiest terrain.
They'll each be towing 160kg of gear as they cross-country ski in minus 50C temperatures.
Their food - dehydrated meat, nuts and meal replacement powder - weighs about 100kg per person.
"That's about 6000 calories a day," Jones said. "We're going to be our own husky dogs."
Castrission added: "That's 15 Big Macs of food worth a day, and we're still expected to lose a tonne of weight, 20 to 30 kilos each."
After training in the Arctic Circle this year, Jones said they were prepared for the deep freeze.
"It's so cold that your breath freezes in front of your face; you get ice forming inside your sleeping bag, it's intensely cold," he said.
He acknowledged their families faced another psychological test.
"It's tough on them but they're proud of us and they're supporting us," he said.
Castrission's mother, Vivienne, had tears in her eyes as she saw her son board a plane to Santiago, Chile.
"They're older, they've got it more together, and the first time's always the hardest," she said.
The adventurers begin their trek from Union Glacier Camp to the South Pole on October 16 and expect to finish by mid-January.
"Spending three months out on the ice with your best mate, you're going to get the occasional tiff but fortunately we've seen each other at our best and worst and we can work through it most of the time," Castrission said.
The expedition aims to raise money for a youth cancer charity.