There is no substitute for fruit juice or smoothie to overcome fatigue at any time, not just during fasting. Usually we start our Iftar with some beverage. Drinking lemonade or tang drink at the beginning of Iftar is not healthy at all.
Rather, fruit juice can be included in Iftar as a beverage, which is healthy. Among these, juice of papaya, wood apple, pineapple, watermelon and strawberry is more beneficial.
Instead of drinking fruit juice directly, you can mix the juice with curd or milk and drink lassi or milkshake. In such a situation, the health benefits of this drink will increase even more. However do not add sugar or jaggery.