I am suspicious he was not at 5 % body fat after the hike. 5 % is extremely low, like really really low, and he used impedance scales as he said in his post.

I use them every day and the fluctuations can be massive due to the water content in the body. And obviously long hikes do mess up hidration a lot.

He should try weighing himself / checking fat % for 5-6 days after the hike on different times of day.

I am not saying his hike sucked - I am envious, I wanna do it ! :)