No you do not have to fast, at least not all day.
We all fast prior to our first meal (breaking the fast or breakfast).
If you nee to take tablets first thing in the morning with a meal you should consult your doctor as you should find that it will unlikely matter when the pills are consumed so long as they are with your first meal or just prior on an empty stomach if advised.
Alternatively you can of course still can eat without effectively breaking your fast on this diet (we fast to mainly control insulin on the Smart Diet).
There is a full list of allowed foods that are very low in both protein and carbohydrates in the meals section of the members menu.
Days marked as '0 Carb' do suggest that you do a full fast if possible but you also have the option of a cleanse or worst case adding protein as late as possible.