Obesity Code and fasting

Hi Brooke.
Just finished reading the Obesity Code and am considering adding in a longer fast every now, maybe a 24 hour fast once a week for starters then work up from there if I want to. (I am currently fasting 18 hours every day.) My concern is that you have said that whatever we do to lose weight, we must continue to do in order to keep it off. I am committed to the 18hour fasts indefinitely but if I start fasting more a couple of times a week to help my fasting insulin levels to drop, will I have to continue to fast that much indefinitely to keep from gaining back the weight?