Coffee and fasting

Articles on how coffee affects intermittent fasting, appetite, energy, and metabolism, including whether black coffee can keep you in a fasted state. Learn how caffeine timing and add-ins (like cream, sugar, or MCT oil) may impact fat loss, training performance, sleep, and hormones important for men’s health.

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The essentials for coffee and fasting — then explore the latest posts below.

Can i drink coffee while fasting? The metabolic rules you need to know

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Nov 30, 2025 · 9 min read

Black coffee generally keeps a metabolic fast intact because it has about 2–5 calories per cup and does not trigger a significant insulin response, so fat burning can continue. The nuance is caffeine’s effect on cortisol and your goal (weight loss vs. strict “autophagy” rules), which can change what “allowed” really means. “From a hormonal ...

Does diet coke break a fast? What the science actually says

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Nov 29, 2025 · 14 min read

Diet Coke typically does not break a strict, calorie‑based fast because it contains about 0–5 calories per serving. But its non‑nutritive sweeteners can still activate sweet‑taste receptors and the gut–brain axis, potentially nudging insulin, gut hormones, and hunger—and quietly dulling some fasting benefits in certain people. “From a pure calorie standpoint, diet soda does not ...