You can have coffee while fasting, but it is best to stick to plain black coffee without any additives like cream, sugar, or milk to avoid breaking the fast. Black coffee contains very few calories (about 3-5 per cup) and does not significantly affect fat burning, autophagy, or insulin sensitivity. Drinking black coffee during fasting might even enhance some fasting benefits such as appetite suppression, increased metabolism, improved brain function, and reduced inflammation. However, excessive caffeine intake or drinking coffee on an empty stomach can cause side effects like anxiety, digestive discomfort, or heart palpitations in some individuals, so moderation and personal tolerance should be considered. For medical fasts or tests, it is recommended to avoid coffee entirely.
