When you resolve the beginning-of-upkeep triggered ability, you first put a hunger counter on Fasting, then you check how many hunger counters it has. If there are five or more, Fasting is destroyed.

You choose whether or not to skip your draw step as that step begins. This ability is now separate from the beginning-of-upkeep triggered ability.

Fasting : règles, fonctionnement et interactions (MTG)

Fasting is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

At the beginning of your upkeep, put a hunger counter on this enchantment. Then destroy this enchantment if it has five or more hunger counters on it. If you would begin your draw step, you may skip that step instead. If you do, you gain 2 life. When you draw a card, destroy this enchantment.

How it works : Fasting

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2008· Wizards of the Coast
When you resolve the beginning-of-upkeep triggered ability, you first put a hunger counter on Fasting, then you check how many hunger counters it has. If there are five or more, Fasting is destroyed.
No other card is named in this ruling.
#2October 1, 2008· Wizards of the Coast
You choose whether or not to skip your draw step as that step begins. This ability is now separate from the beginning-of-upkeep triggered ability.
No other card is named in this ruling.