You pose interesting questions. Fasting can be OK for specific body types but if you are very thin or dealing with diabetes or another major health issue, it is best to seek the advice of a Naturopathic Doctor before starting.

From my understanding you are required to have short day fasts during Ramadan and then you eat after sunset. In this case, it would be best to eat long burning complex carbohydrates when you break your fast. Avoid sugar or refined white rice and flours. Whole grain rice and non-gluten grains such as millet, amaranth or quinoa are a good substitutes.

Be sure to include healthy sources of fats such as coconut, hemp, organic ghee or organic olive oil. Do not eat trans fats or refined oils such as canola, corn or soy oils. Do not eat anything deep fried. It is very hard on the body to go from a fasting/cleansing state to processing denatured foods in just a few hours.

Be sure to include healthy lean proteins such as lentils, beans, raw nuts and seeds. Do you have a restriction on fish?

Be sure to remain hydrated with pure water (not distilled as it can leach minerals from your bones) and if you have to work, make sure you do not need to do anything too taxing such has heavy lifting or work you need to concentrate on. Your body is going through a time of purifying itself when fasting and it is using all of its reserves for that process. Also your blood sugar will be out of balance and you can become fatigued easily.