In Tantra, we are feeding the yidam when we offer the food to collect merits or to feed the body so that it is able to do lots of Dharma work to benefit others.

Nevertheless, even our meals can be a spiritual practice. I am not sure if it is really a necessary vow that is practices in all Buddhist traditions because the emphasis seems to be on outer physical practice as some Mahayana traditions placed greater emphasis on the cultivation of inner qualities instead and vows that had been correspond to this. The permissible food & drinks for the Bhikkus The eight types of drinks: Drinks made from Mangoes, Drinks made from rose apple, Drinks made from seeded bananas, Drinks made from seedless bananas, Drinks made from grapes, Drinks made from raisins, Drinks made from fruit of water lilies, Drinks made from fruits of spiny trees like Indian plum ( Uguressa in Sri Lanka) and Indian date/ jujube ( Masan in Sri Lanka). They cannot be cooked and given the syrup since cooking makes them impermissible. They have to be made using water and sugar/ jaggery (solidified treacle or honey). Apart from those ‘eight types of drink’, juices from small fruits such as lime, orange & tamarind are also permissible. From noon to the following morning, they can have only permissible food & drink called ‘ Gilanpasa‘ The ‘eight types of drink’ (‘ Ashta pana‘) are the main permissible drinks. It usually is limited to breakfast and lunch (eaten before noon). From TheBuddhism.Net According to our Great Buddha’s disciplinary rules for the Buddhist monks and nuns, they can only have proper meals from sunrise to noon.

Bodhi pooja gatha in sinhala