A quasi-rank 7 creature was the best food for a body in the upper tier. The stuffed winged beast only had its skin left, but that resource could boost Noah's power by a lot.
Ordinary magical beasts would find it hard to digest a resource on that level, but Noah's body didn't have those limits. His black hole also helped in that process and made him absorb the energy contained in the winged beast's skin in no time.
Still, the actual improvement of his tissues arrived slowly. The black hole had to purify the energy absorbed from the skin and redirect it to every corner of his body. Then, it had to harmonize that growth so that Noah could obtain the best out of that process.
Noah mostly trained while his body grew, but his mind continued to imagine battles against the Snakes' leader during the whole process.