Why does Obito look like an adult during the Kyuubi attack on Konoha? In the series, it is stated that Kakashi was 26 when he became the leader of Naruto's squad. So following that, he was 14 when the Kyuubi attacked the village. Seeing that Obito was the same age as Kakashi, he should be 14 but he didn't look like it. How old was Obito at that time? It shows him as an grown up, adult man. Is this because of Zetsu covering him or is he just older than Kakashi?

This is not a question directly about the age of Obito but also why he looked older. In my understanding Kakashi and Obito are about the same age. I don't care when Kakashi became a Jounin because that is not relevant to this question.
The difference in age between Obito and Kakashi has been explained in this answer.

From this thread on narutoforums (emphasis mine):


  It is impossible for both Kakashi and Obito to have been 13 during the Kakashi Gaiden, because there is at least a confirmed 4 year age difference between Kakashi and Obito when they were confirmed to both be Genin teammates during the Chuunin Exams. They entered the academy the same time, and they all graduated the academy together as teammates. Kakashi was at least 4 years younger than both of his teammates at all times. There is no possible way that Kakashi was a 13 year old Jonin during the Kakashi Gaiden.


Since Kakashi is younger than Obito, obviously Obito will look older.