Yes, you can drink black coffee while fasting. Black coffee is almost calorie- free (about 3–5 calories per 8 oz) and does not contain fat, protein, or sugar, so it won't break your fast by triggering digestion or raising insulin levels. Drinking black coffee during fasting can also support benefits like appetite suppression, enhanced fat burning, improved brain function, and increased autophagy (cellular cleanup). It is best to drink plain black coffee without any additives like milk, sugar, cream, or sweeteners which can break the fast. Moderate intake of 3–4 cups per day is generally safe during fasting periods, but excessive caffeine should be avoided to prevent side effects like heart palpitations or sleep disturbances. Black coffee also contributes to hydration though it shouldn't fully replace water intake. In summary, black coffee is allowed and can even enhance some fasting benefits, as long as it is consumed plain and in moderation during the fasting window.