On Monday, around 4 a.m., Enes Kanter will wake up, eat a light breakfast of yogurt, fruit and peanut butter, and drink as much water as he can. Then for the roughly 16 hours between sunrise and sunset in Portland, Ore., the center for the Portland Trail Blazers will abstain from eating, drinking and taking medicine, even for the shoulder he separated almost two weeks ago. For Kanter, a Swiss-born Turk who has fasted for Ramadan while playing competitive basketball for the past decade, the routine is nothing new. But this time, the circumstances may be: Never before has he fasted while playing in the N.B.A.’s postseason.

This year, with Ramadan beginning on Sunday, his fast will come during Portland’s second-round series against the Denver Nuggets. He’s averaging nearly 20 points and more than 10 rebounds per game against Denver, and has been a surprise difference-maker for the Blazers behind Damian Lillard.

In Islam, Ramadan commemorates the month that God started to reveal the Quran to the Prophet Muhammad, and each year roughly 1.5 billion people observe it through daytime fasting, during which smoking, sex and chewing gum are also prohibited. In Muslim-majority countries like Turkey, where Kanter grew up, businesses and schools often adjust their hours to accommodate the observance. In the United States, it’s business as usual for most of the estimated 3.45 million Muslims, including Kanter. He’s become accustomed to fasting by himself.

The first time Kanter observed Ramadan while training seriously for basketball, he was 16 years old, living in Turkey and playing for a team with an international roster. That year, Ramadan started at the end of August — each year, it moves back by about 11 days — and the first two-a-day practice was grueling for Kanter.