I think the idea is that it's the last option, at least that's how I play with the mechanic, if I'm low on HP I may strip to charm them for a tick and attempt escape or use some other tool, like a wand and depending on the situation I go for sex, perhaps only in the first few floors if I find gear that requires a lot of STR I sex some goblins or slimes to increase Luck to get the Rerolls. Even without finding a Scroll of Tentaculation early, doing that will help a lot going further down the dungeon.
Ring of Regeneration on the other hand is extremely useful, it helps you sustain in combat, and blessing that ring makes it even better.
The thing with the Calories is that the game expects you to economize your movements by using the diagonals, the first runs I did lose over hunger, but as soon as I played the game with the numpad and explored the maps with the intent of routing my movements instead of going blindly at it, I started to Ignore the Calorie count, and only ate a sandwich when I got the prompt alerting it was low. Some runs you are low on sandwichs some runs you may not, but completing all the floors available as of now it's very doable if you are smart about your exploration and combat choices. But the important thing, from my experience thus far, the game IS a game still and not just window dressing for the lewd content. I agree though that Ring of Calories is not useful as of now.
