The Didache orders the baptizer and candidate to fast before baptism and distinguishes Christian fast days from those of its opponents (Didache 7–8). Tertullian, Basil, Chrysostom, Augustine, and Leo all treat fasting as a normal discipline, even while disagreeing about which observances bind and how strictly.
The patristic case is not that every Christian must follow one universal menu or calendar. Nor is hunger itself holiness. The Fathers are relentless that fasting joined to anger, vanity, or neglect of the poor misses its purpose. Still, a Christianity that treats fasting as dispensable in principle sits awkwardly beside both the earliest church order and the later consensus.
Primary sources
Didache 7–8: https://www.newadvent.org/fathers/0714.htm
Jerome, Letter 22.37: https://www.newadvent.org/fathers/3001022.htm
Cyril, Catechetical Lecture 4.22: https://www.newadvent.org/fathers/310104.htm