I have a colonoscopy thursday. i can't eat all day tomorrow. can i drink slim fast for some calories?

I wouldn't: If your doctor advised you not to eat the day before then you should not. The bowel prep will clear everything out. Make sure you are meant not to eat for the whole day prior and not just 12 hours before the procedure.

Yes: The purpose of limiting diet prior to colonoscopy is to have a relatively clean bowel when the scope is passed for visualization of the bowel lining. Solid foods should be eliminated but liquids should be used to prevent dehydration. On the preceding day oral GOLYTLY is taken and in many instances a Fleets enema is also used. No problem in using Slim Fast