Sounds like something is going wrong - a good closed lop set-=up should mean you can eat more normally.
If you have insulin resistance (bad absorption) or cannulas that don't work well (I had this problem with Omnipod sadly as I love them) or the insulin isn't suitable, its worth looking into.
What insulin are you using, how long have you been a T1, and are you injecting or inserting cannulas into the same site repeatably?
Once the loop is configured you should need to input only when you eat - then expect a rise which is treated quickly and bought back into line. If that not happening there is something not working right yet - so needs work (don't give up)!