Ihoujin, Dungeon ni Moguru - Chapter 066.1: The Trapped Adventurer III – Part 1

I may be a virtual YouTuber, but I’m practically an office worker. You’re saying I have the most subscribers in the group, except for the boss? Well, all those subscribers are on the official account, so it doesn’t really mean anything. Why haven’t I made an official debut? … So, what can you actually do about it?

Oscar, a destitute young boy, died in a tragic accident and was reborn in the forgotten realm. As a member of the lowly Birch tribe, his solace comes from the fragments of a guardian's spirit, residing in his soul. After the decimation of his family in the hands of a powerful race known as the dreads, he embarked on the part of revenge, leading him to the path of transcendence.

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

The MC entered the body of the An family eldest son, An Ziran, an arrogant 16 years old boy who weighed 78 kg (~171-172 lbs), who only knew how to eat, play and sleep. Seeing his current body, An Ziran decided his first priority was to LOSE WEIGHT!