I m trying to eat a low residue diet because of a colonoscopy I'm having n a couple of days (doctor didn't recommend,doing it voluntarily)?

The doctor should have given you instructions on what to do before the colonoscopy. As long as you follow the actual instructions given to you by the doctor, nothing else matters and everything will be fine for the test.

I have never had one. A friend of mine recently had one and his doctor told him to have liquids only starting at noon on the day before his procedure. Other than that, he didn't need to do any special diet during the week before the procedure.

So, again, just follow what ever instructions your doctor told you and everything should be fine.

You're not supposed to eat for 24 hours before the colonoscopy. You also have to take laxatives mixed with gatorade that will make you pee from your butthole.

Fat is not residual, anyway it is normal to be prescribed laxatives before.

You might want to discuss this with your doctor.