Wouldn't it make sense to eat some complex carbs on these days (at evening around 18h)? Insulin levels should have dropped already by 23 h when im going to bed?
So you're asking to eat Low GI carbs? If that's the case, no. From the book, you're wanting High GI Carbs in the evening time. Even on off days while on DB.
Complex carbs no, but I wouldn't necessarily fear low GI or Glycemic load carbs. IMO off day carbs should be focused towards refilling liver glycogen (since theres no training induced Glut4 translation) which sugars do better than starches.So ice cream (in some amount), milk, sugar, fruits etc would be perfect. Again IMO, because you aren't likely to be directly sending the majority of carbs you eat towards muscle glycogen you should avoid starches on off days.