You notice that you find it difficult to pray whenever you are fasting because you feel so tired and weak because of the hunger you are feeling then this is what to do.
What you need to understand is that fasting without prayers and studying the word of God is like hunger strike, because the goal of fasting is that you deprive yourself from food and feed your spirit.
The Bible said in Acts chapter 13:1,
It says the apostles were fasting and they were ministering to the lord in prayers and worship and the next thing the Bible said the holy ghost spoke to them, meaning there's a kind of direction you receive through revelation whenever you give yourself to fasting.
This is the key. No matter how tired you are set out time to pray before you break your fast. Prayer in itself is very powerful but if you had fasting to that prayer you are praying I tell you the truth you are going to receive quick and urgent results that's really going to surprise you.
Fasting is a very strong weapon in the spirit whenever you notice delay to the answers to your prayers.