How John 12:47 does not contradict John 5:22
Yes. According to canon 1251 of Code of Canon Law, "Abstinence and fasting are to be observed on Ash Wednesday and Good Friday." So absitence from a certain food (preferably meat) and fasting (1 full meal and 2 small meals) are necessary for those who are 18-59 years old (Can. 1252). Otherwise, it is mortal sin.