op, it will be much more beneficial for you to eat clean, not pizza and ice cream. cell tech will help you gain muscle but it will not make you cut weight if you are not doing your part with the...
ive seen plenty of videos of pro bodybuilders lifting with dog sh_t form, doing partial reps that look sloppy as hell, and apparently that can work for the sake of keeping tension on the intended...
There are lots of different options, but i like doing steep decline sit ups, steep decline side crunches, russian twists, standard crunches and leg lifts.
dont take this the wrong way, but that is entirely inadequate. you should have a routine that beats the crap out of your core with exercises that focus on upper, mid, lower and obliques.