Also keep in mind that ancient religions don't always match cleanly with what we expect out of modern ones.

Especially the idea of deific exclusivity. If you have always believed that your gods and your neighbors gods are different and war with one another just like you and your neighbors do, then maybe they lost along with you.

Plenty of stories about gods dying, probably feels better that your gods died trying to save you than ran off and abandoned you.

Just one speculative example, but no one today would assume that a personal problem is because their religion got annihilated, maybe not so much with all the numerous past belief systems.

You stop eating for a day. Total caloric deficit.

Your day to day energy is stored in glycogen a kind of easy to access sugar that is stored for a bit but easier to metabolize than body fat. This is replenished from food you eat. So if you don't eat then your body will start pulling energy from your fat stores. This small amount of energy is basically packaged with a bunch of water for important chemical reasons but the water makes it heavy. Your body also keeps water based on your current salt content.

So what has happened at the end of your one day fast it that you have used up all of your glycogen releasing all that heavy water it was tied too and your salt content has dropped because you haven't eaten anything to replace it. So you'll pee out more water so you body keeps the salt concentration it likes.

Your day of burning calories burned some fat depending on your level of activity. But less than a pound. For most people significantly less than a pound of fat per day of complete non consumption.

But when you step on the scale you and most other people will see that you have lost somewhere between 2 and 5 pounds. Because you pissed them out for reasons only tangentially related to your goal.

That's water weight. Your body will hold on to that same amount of water the very next day when you celebrate with one slice of salty pizza and make it look like you've lost all your progress. Thus why understanding water weight can help someone trying to slim down because it can be really demoralizing not knowing why daily results seem to bounce around so much.