Does dieting affect your menstrual cycle?

I've been on a diet for two months now.

I am exercising and controlling my diet.

I am trying to reduce the amount I eat compared to usual, but

Can my menstrual cycle be affected as well?

My period used to be regular, but since starting a diet, the flow has thinned out and my period is starting late. I'm worried because my overall condition has been consistently poor.

Should I go to the hospital?