Age 52....I'm Getting Ready For A Colonoscopy In The AM.

Age 52....I'm getting ready for a colonoscopy in the AM. I'm 120 lbs...my husband is 240 lbs. Why do I have to take as much of the colon cleaning medicine as he did? I drank half the dose and 2x that much water and have been to the restroom 10 times in 30 min...nothing is left inside me ...all is clear. Why do I have to drink the rest. Plus, I have to do it again in the AM anyway.