The original article from Herald Sun (which feltet.dk is quoting) states that he went from 59 to 68 (-ish) kgs - not 78, as was stated in the feltet.dk article. That makes it somewhat more believeable, I guess.
For aanyone interested; http://www.heraldsun.com.au/sport/aussie-tour-de-france-contender-richie-porte-says-hes-more-hungry-than-ever-as-he-recovers-from-terrifying-crash/news-story/906bb8b0d78130c830e5d53f6d0a3784"Porte put on more than 10kg inside a month, but makes no apologies in the belief it’s not just the legs that benefit from a break.
“I got out to 68kg, probably even more to be honest. I left the Tour at just under 59kg,” he said.