It is a requirement to have the food week, basically it's so your body doesn't go into starvation mode.
It doesn't have to be actually food, it can be a certain amount of milk ontop of your packs as well, and if you do it the way you're suppose to - low carb, or just adding safe ketosis foods to meal packs, it won't affect your weight loss because you're still under your allowed calories that allow you to lose weight.
There's more accurate information on the Exante website so I'd recommend looking there.
Well done on doing 10 days 100%!