Potatoes and weight gain

Hi

Am currently at Step 1 having come across potatoes not Prozac originally because I wanted to lose weight but now recognise the reasons why ive yo-yo dieted in the past. However am freaked by step 4 and a potato before bed. Will this not lead to weight gain? So much diet literature talks about not having carbs after 6pm. Having trouble having faith in this part of the programme. Can anyone reassure ?

Susan :h2)