I saw an episode of the Portuguese version of Naked and Afraid this past summer in which one of the contestants, while in the jungle, was so freaking good at living like in the stone age that he created a hut on a tree complete with animal fur, banana leaves and a bamboo bridge to another hut he built on top of another tree nearby.
Neither his partner nor him lost any basal weight during the 2/3 weeks. They had a rather constant diet of protein, sugary starches, fish and even bananas and honey. They even got it on off the camera.
THAT was impressive.
Granted it helped tremendously that the female was compliant, helpful and non-bitchy, otherwise the guy wouldn't said "fuck it" at the beginning. Which is what most guys in Naked and Afraid do... you can tell by their faces after the first low carb-induced argument.