I am so glad you asked. It shouldn't but I guess that will depend on you and how you eat after you reach your goal weight. My diet plan is more than a diet plan, it is a LIFESTYLE CHANGE. You can follow my basic plan forever with a little more leeway and flexibility for maintaining weight as opposed to when you are losing it. So no, you shouldn't gain your weight back unless you go and do something crazy such as eating the way you were before my diet.