Mateus 6

Jesus taught about abstaining from food.

16 "When you abstain from eating food in order to please God, do not look sad as the hypocrites look. They make their faces appear sad in order that people will see that they are abstaining from food and will think highly of them. Keep this in mind: People will think highly of those people for that, but that is the only reward those people will get! 17 Instead, each of you, when you abstain from food, should comb your hair and wash your face as usual, 18 in order that other people will not notice that you are fasting because you will look as you always do. But God, your Father, whom no one can see, will observe that you are abstaining from food. God your Father sees you even though no one else sees you, and he will reward you."