I encourage you to consult a doctor, but obey God first.
Pray first. Not your will, but let God’s will be fulfilled in your life.
Humble yourself and have an attitude of “surrender”. Fasting doesn’t make us better than someone who doesn’t fast. Don’t let religious pride sneak in. Fasting is for our good and benefits our relationship with God. It gives us a new perspective when we are not seeking to please and indulge our flesh.
Prepare your schedule for more quiet times with the Lord and longer Bible studies and devotionals. You will be surprised at how much you start hear from God during the fasting. Through fasting your spiritual hearing disabilities may be gone.
Fasting should be done secretly, but I let my family and friends know if I am on a long fast for two reasons: 1) For them to support me and pray for me during this time. I ask them to not offer me food (“Please don’t tempt policy”). 2) Another reason I tell people is so that those who are close to me don’t get offended if I don’t accept their invitations to any events that involve food. I believe as long as you are not announcing and bragging about your fasting it is ok to ask for support. Always check the motivation of your heart. Fasting has to humble us; we have to not feel superior to others who are not fasting.
Quiet all the voices that will come against fasting. I cut down unnecessary texting at least 70%. And I can’t tell you what a difference it has made in my life. I became more productive and have more time for my family and for the Lord. I suggest that you do the same, at least while you are fasting.
The enemy will bring many oppositions! Please know that you may have temporary headaches, sleeping disorders, bad breath, moodiness, and/or black outs (walk and get up slowly) at the beginning. You may even be easily irritable due to lack of sugar or carb intake. The enemy will throw anything at you to make you quit. He will tempt you in any way. Be mentally prepared to face many temptations to make you break your fast. In the past, the enemy would try to put a fear in my heart and mind that I was going to have a heart attack while fasting. Remember, he is the father of all lies, as Jesus called him. Please be prepared and be very mindful of him using people to hurt your fast.
I suggest for you not to go to any special event where there is food. Why? Because the first three days of fasting are especially difficult. After that three-day mark, you typically don’t look for food. After seven days, your body generally adjusts and you will not be easily tempted.
Quiet your surroundings, at least at the beginning of your fast. The more stressed you become, the more likely you will look for comfort in food. I have been there. I have broken fasts while under huge pressure. I am telling you this so that you understand that this is a journey. We fail and then we get up and try again until we conquer. Our God is merciful!
Also, consider going on a shorter fast to train your body before you go on a radical fast such as a 40 day fast. For example, you can do a juice fast if you have never fasted before (where you only drink healthy juices as a substitute for your usual meals). Then you can go on a seven-day water fast. Then you seek the Lord to fast longer. Work your way up. But again, if God is calling you, you have to obey Him and He will sustain you.
During the fast, DO NOT gossip (we shouldn’t gossip anyway) and quarrel or fight. DO GOOD to others; Defend the oppressed and fatherless.
According to Isaiah 58:2-12 NIV:
“For day after day they seek me out; they seem eager to know my ways, as if they were a nation that does what is right and has not forsaken the commands of its God. They ask me for just decisions and seem eager for God to come near them. ‘Why have we fasted,’ they say, ‘and you have not seen it? Why have we humbled ourselves, and you have not noticed?’ “Yet on the day of your fasting, you do as you please and exploit all your workers. Your fasting ends in quarreling and strife, and in striking each other with wicked fists. You cannot fast as you do today and expect your voice to be heard on high. Is this the kind of fast I have chosen, only a day for people to humble themselves? Is it only for bowing one’s head like a reed and for lying in sackcloth and ashes? Is that what you call a fast, a day acceptable to the Lord? “Is not this the kind of fasting I have chosen: to loose the chains of injustice and untie the cords of the yoke, to set the oppressed free and break every yoke? Is it not to share your food with the hungry and to provide the poor wanderer with shelter— when you see the naked, to clothe them, and not to turn away from your own flesh and blood? Then your light will break forth like the dawn, and your healing will quickly appear; then your righteousness will go before you, and the glory of the Lord will be your rear guard. Then you will call, and the Lord will answer; you will cry for help, and he will say: Here am I. “If you do away with the yoke of oppression, with the pointing finger and malicious talk, and if you spend yourselves in behalf of the hungry and satisfy the needs of the oppressed, then your light will rise in the darkness, and your night will become like the noonday. The Lord will guide you always; he will satisfy your needs in a sun-scorched land and will strengthen your frame. You will be like a well-watered garden, like a spring whose waters never fail. Your people will rebuild the ancient ruins and will raise up the age-old foundations; you will be called Repairer of Broken Walls, Restorer of Streets with Dwellings.”