Avoid sugar at ALL costs. Read labels carefully, you will be amazed at the amount of sugar food companies put into processed food. There is a very good reason they do this, they know sugar is addictive. Avoid simple carbs like pasta, bread, rice, potatoes on fast days and even on non fast days treat these staples as sometimes treats. For you fast days have protein (tuna, fish, chicken) and fat (high fat low sugar yogurt, avocado)and lots of green bulky vegetables or salad. It will keep you satiated for a long time.

Personally I would limit fruit, stick to the berry type fruits as they have less sugar content. Never have fruit juice, all the fibre has been taken out, its just sugar water. Always have whole fruit, never dried fruits.

Good luck with it, it works. Lost 44 pounds in 12 months. Now doing 6:1 maintenance.