Evidence from fasting from the Church
“By bodily fasting Gods curbs our vices, elevates our minds, and bestows upon us virtue and its reward.” (Pope Gregory the Great, Liber Sacramentorum in PL 78:55C; also in the Preface for Lent in Missale Romanum, 21st Ed.)
“Fasting purges the mind, elevates sensibility, subjects the flesh to the spirit…makes the heart contrite and humble, which God does not spurn, It disperses the clouds of concupiscence, extinguishes the flames of lust, intensifies the light of chastity, It dislikes verbosity, renounces a superfluity of riches, treads upon pride and commends humility.” (St. Bonaventure, Defense of the Mendicants, toward the end of Ch. 6)
“Fasting is the teacher of continence, the discipline of chastity, the humility of mind, the chastisement of the flesh, the form of sobriety, the norm of virtue, the purification of the soul, the expression of compassion, the foundation of gentleness, the origin of chastity, the grace of old age, the safeguard of youth.” (S. Ambrose, De Helia et Ieiunio, ch. 8, n, 22)
Hope is not a virtue for people with a full stomach. (Pope Francis, 27 Sept 2017)
"Indeed, penance is that counterforce which keeps the forces of concupiscence in check and repels them. In the words of Christ Himself, “the kingdom of heaven has been enduring violent assault, and the violent have been seizing it by force.” (Pope Saint John XXIII, Paenitentiam Agere, 10)