"I met with him early this morning, and he is simply in tip top shape," said Rupert Gerzer, head of the Institute for aerospace medicine, a branch of the German Aerospace Center (DLR).
The 38-year-old Gerst landed yesterday in Kazhakstan after living for the last 165 days in the International Space Station (ISS). He flew into Cologne on Monday night and is being kept at the DLR headquarters until doctors declare him fit to finally spend a night in his own bed.
"I would be surprised if he wasn't allowed to go back home tonight," Gerzer said.
Andreas Schütz, spokesman for the DLR, said that Gerst returned to Germany very healthy and robust on Monday night. The astronaut took to Twitter to announce his homecoming.
Gerzer said that Gerst's top physical condition was likely due to his dedication to doing the recommended training while onboard the ISS.
"It's quite obvious that trained well and is obviously one of those people that does not get sick easily," Gerzer said.
Gerst travelled back to Earth in the Soyuz TMA-13M spacecraft with his comrades Reid Wisemann from the US and Russian Maxim Suraev.
Upon his arrival back in Germany, he told reporters he already missed floating, adding that when he wakes at night, he'll definitely wish he could simply float to the toilet like he did in space. Gerst is also looking forward to meals of pizza and hamburgers, but only when he gets the okay from his medical team.
The Mayor of Cologne, Jürgen Roters, congratulated Gerst on his return as well as the timing of his homecoming: Tuesday is the opening of the Karneval season, which kicks off in the Rhein area every year at 11:11 on November 11.
Other astronauts are known to struggle with a return to gravity. German astronaut Reinhold Ewald, who flew to the Mir space station in 1997, said his reintroduction to terrestrial conditions left him fighting with circulation and orientation issues.
The DLR said it generally takes a year to recover from all effects of weightlessness.