1 Pound no Fukuin

Hatanaka Kosaku is a talented boxer who turned pro at the age of 19, winning his debut match with a first-round KO. He is talented, but he has no guts. His uncontrollable appetite is an even bigger problem. He can't put himself in the right weight class, he runs out of energy because of hunger, and he gets knocked out while his eyes are set on food at the ringside. However, Kosaku's life changed when he met Sister Angela, a novice nun in the convent near his boxing gym. She became the source of his power, and Kosaku fights only to win her heart.
(Source: IMDb)
~~ Adapted from the manga "One Pound Gospel" (1ポンドの福音) by Takahashi Rumiko (高橋 留美子).