fasting relation to days

 Sunday - sun -  victory, as in the case of disputes and court cases, but also when starting Vedic studies or a journey, health 

Monday - moon - Shiva - spiritual purposes. 

Tuesday - Mars - Shree Karttikeya, victory, childbirth, kids, children and health. 

Wednesday, Budhvar, belongs to Mercury. It is mostly dedicated   toward   education   and   success   in   business.  

 Thursday - Jupiter - education and scholarship. 

Friday - Venus. prosperity marriage 

Saturday - Saturn - longevity.

https://dipika.org.za/wp-content/uploads/2015/04/Hinduism-on-sex-when-fasting-.pdf