Hi AnnaandAlfie, welcome! I will let the more experienced posters give you the benefit of their wisdom on all this as well but as far as I am aware, the recipes in the book do include some carbs and each person has a slightly different response to carbs from different sources… so I think it’s a case of try, test your BG (if you do) and see what works, as long as it’s in the 800 calorie count.
Not sure if this helps but the GI lists (there are loads available) show the likely impact of a food on your blood sugar – this is one site but you can also do a search on an individual food, for example ” melon GI ”
http://www.health.harvard.edu/healthy-eating/glycemic_index_and_glycemic_load_for_100_foods