After Bear drops the men off on the island, the enormity of their task begins to dawn on them.

It's been 48 hours since the men had a meal and hunger grips the group. The race is on to bring food back to camp before they become too weak to hunt.

With the men losing weight on a diet of just 300 calories a day, Ryan heads off alone in search of food, and finds himself lost and in imminent danger.

Three weeks into their survival experience, the group are barely getting by on a meagre diet of snails and coconuts; Mike and Chris battle with dangerous tides.

The men enter their fourth week of living on the island with the group hungry and divided. They elect an island leader. But will everyone back him?

Bear Grylls visits the men at the end of their stay on the island to explore how they coped and how the experience has affected them.