This is one of those power-fantasy stories where the main character is indeed overpowered but misunderstood by everyone else. The mc, Mars, is a prince who's position for the throne is weak after the corrupt prime minister managed to marry his daughter to the king once Mars's mother died. The prime minister, obviously wanting to strengthen his position by making his grandson the next king, constantly poisons young Mars's food and many taste testers at the palace have quit their jobs. Not wanting to be poisoned or starve to death, Mars sneaks outside the palace every day and hunts weak monsters to eat. Although theytaste terrible (and he threw up many times), he didn't think much of it because he was so hungry. Little did he realize that monster meat was poisonous, and that eating it would kill the average person...and there's more that goes on after this but basically, he eats lots of monsters to gradually grow stronger and gain allies.

I would recommend reading this if you enjoy power-fantasy slop, but there are definitely far better op protagonist light novels out there, including The Eminence In Shadow, That Time I Got Reincarnated As A Slime, Arifureta, etc.