DIAMOND45

So my issue is kind of weird to me. I have been on my pre-op diet for 13 days now and for the last four days I have only been able to drink 2 of the four protein shakes that I'm suppose to have, because for some reason I just am not hungry. I do have a cup of broth each day and I drink plenty water and other sugar free drinks, but I can't seem to get a hunger for those other 2 shakes. Has anyone else experienced this and is this normal?