You don’t need to buy the book but it will definitely help get your head around the concept. I also recommend the Obesity Code by Jason Fung. Pick your two fast days and stick to them. You don’t have to eat healthy but it helps a LOT to do so.

There is a lot of debate on this site with what constitutes healthy. Ask most of the fasters that have achieved their goal weight and are in the maintenance phase (Ive been in maintenance mode since march this year) and their response will be similar. No sugar!!! So that means no fizzy drinks, orange juice, cakes, biscuits, chocolate lollies etc. Also I do not think that any processed grain based foods are healthy (this is an area of debate by those starting 5:2 not so much with those that have achieved success). So grain base foods are bread, pasta, pizza, crumpets, breakfast cereals (really bad) etc. Limit rice to a minimum. Some fruit and go for your berry types fruits. Get your carbs from veggies. Some meat and fish is good. fats like cheese, high fat low sugar yogurt, avocadoes, nuts like almonds, walnuts, brazil nuts. legumes and beans but not the crappy stuff in cans which are full of added sugar.

Good luck it works if you want it to.