The emperor penguin (Aptenodytes forsteri) is able to fast for months, in conditions of extreme cold, during the hatching of the egg. And it is the male who does it.
At the beginning of winter, the penguins of this species gather on the ice inside the Antarctic continent, the females lay their eggs (only one each) and then go to sea. (See the best pictures of the penguins)
The males remain and each one takes care of the egg he fertilized, holding it between the legs and covering it with the abdominal folds, or the folds of the belly. The penguins thus remain, tightly held in a tight group to defend themselves from frost and wind, for more than two months, fasting until the egg hatches. Shortly before this event, the females return, well fed, each with its male and its egg. When the child is born, the mother feeds him and at that point the male goes to the sea in search of food.
(Is it true that snakes fast for a year?)