Smoothies: Boost the health benefits of your fast with our liquid meals. Just blend and go! 243 calories and under. This healthyrecipe is featured in the smoothie section of the new 5:2 Starter's Guide to The 2-Day Diet. The book provides a selection of over 100 tasty recipes to help you meet the daily 500 calorie allotment for the 2 days of intermittent fasting, as required by the 5:2 Diet.