I think you are right and most major religions encourage fasting, for a variety of reasons.
Christians traditionally fasted during Lent - the forty days leading to Easter. Not complete fast for forty days! I think it took the form of eating less, perhaps time-limited eating as you do? And many people used to inflict some additional form of discomfort, such as putting a heavy chain around their body to carry about for the duration of lent. To share with Christ the burden he had to bear carrying the cross to Calvary. Or the hair shirt - wearing an uncomfortable undergarment to bring about mindfulness and humility.
Another early Christian practice was vegetarianism. Very devout hermits or religious men completely avoided eating flesh. But that was a hard sell with the medieval general public, so instead religious leaders suggested one meat-free day each week. Friday. But, that idea was further eroded and meat-free Friday was re-interpreted as fish-eating Friday. Ingenious, rather legalistic way of getting round an imposed restriction? I believe many Roman Catholics still avoid meat and instead eat fish on Fridays? And it must be the reason why, as a child, I was repeatedly offered fish when I ate at friends' houses - the Mother would insist that vegetarians can eat fish. Witness the young child insisting, 'No, a fish is not a vegetable!'
Muslims are supposed to fast every day from dawn to sunset during the month of Ramadan. Fasting requires complete abstinence from sex, food, drinking, and smoking. However, having worked for a few years in a Muslim environment it was clear that not all Muslims follow the practice. And for those that did, there were interpretations. For example, they would fast from dawn to sunset Mecca time, which meant they could eat freely12 hours per day. Oh, I will never forget the gluttony that followed the expiry of the fasting hours . . .
So, I have rather mixed feelings about religions imposing fasts on adherents.
