I'm sure u respect their choice of free will for them to believe in their religion although your most hoping they believed in Jesus to. Therefore u should tell them u are fasting, and fasting for your own growth and devotion to Jesus. So that they realise and respect what u are doing as u have respected them for their own free will. In doing this they will also not prepare too much food that u'll be forced to eat out of politeness and respect because they made it for u. Because now that u have told them what u are doing they know what you are trying to achieve and will not make your share of food for the few days u've elected to fast.

I think its okay to let family know u are fasting, i believe its when u go out saying n boastin that u are fasting to gain sympathy or status from people that u don't know that, that is wrong. So by all means let your family know.

Remember that when we live for Jesus, we should not be afraid of what others think of us, even our own family. Be right with the Lord and he will look after you no matter the case. Read Matt chapter 10 verses 32 to 40. Read verse 37 especially.

Remember that we are not fighting against one another but against the prince of evil and his dark forces. If you are told your not allowed to fast in your household by your parents, i then think it is best to do as they say. For God says obey your parents. Now when we obey our parents are we not obeying God =) are we not glorifying His name ! In that, u will have shown God that u do love Him and obey His words. Because this is a delicate matter >< and u don't want to stir trouble in your own family i think that is what u should do if your not allowed to fast. So that they may see the work of God in you. That being you obeying them. Hopefully through this and other well meaning things u do, they might be brought to Christ Jesus ^^ and receive salvation.

How ever if they just think your weird or say nasty things for you fasting but still permitting you to fast. By all means continue fasting and forgive them of their insults for they do not know better as of yet. But through your deeds and walk with Christ they may begin to realise what they have done was wrong and repent and be saved ^^. I wish u the best =D ! GOOD LUCK. GOD BLESS !

BTW When we are fasting =P it is an alotted time between yourself and God, u dedicate these moments to Him. Do not get distracted by other things during this time. Pray to God, worship and praise Him and feed on his spiritual words read the Bible seeking His will. If you are fasting for healing that is what u should pray for during your fast. If your fasting to draw closer to the Lord God pray that he draws you near n gives u understanding during your fast. ^^ God Bless hope this helped in some way.

Forgive me if i've said anything incorrect i am still new to His words, and this is my understanding of now. Read what i have written and see if it is right in your own eyes. If it is not continue searching for answers n pray that the Lord reveals them to you =) and then if u so desire offer me your corrected opinion on what i have written, that would be great =) then i could learn to XD.

GOD BLESS GOOD LUCK IN YOUR FASTING ^^.