What is the ruling on one who does not give his body its due in terms of food, drink, and care, and is he sinful for the weakness of his body despite the availability of blessings?

A Muslim must give everyone their due without excess or negligence, and preserve their body and health, eating and drinking what wards off harm and injury. If one refrains from food and drink until they perish, they would be considered a killer of their own soul, unless it is an act of asceticism and humility before Allah Almighty after having fended off harm.