Anyone know of a good detox that doesn't make you lose weight?

I know that is probably a contradiction – a detox that doesn’t make you lose weight, but i’m quite a skinny girl and don’t want to become invisible; i lose weight easily, however i’d love to do a detox as i think i have IBS and my bowels and stomach need a clean, it’s driving me crazy.
Everything I eat causes me cramps at the moment.

Does anyone know of a good diet that cleanses the body but doesn’t make you lose weight?

Thanks!