Intermittent Fasting Window & Eating Schedule Calculator

Intermittent Fasting Guide

What should I know about Intermittent Fasting Protocols?

16:8: most researched and popular protocol. Fast 16 hours (including sleep), eat within an 8-hour window. A typical schedule: last meal 8pm, first meal 12pm. 18:6: more restrictive eating window. Often used when 16:8 results plateau. 20:4: significantly restricts eating opportunities — requires meal planning. OMAD: one meal per day. Very restrictive, difficult to meet nutritional needs. 5:2: eat normally 5 days per week. On 2 non-consecutive days, eat only 500-600 kcal. Each protocol can achieve similar results for weight management if total weekly calorie intake ends up similar — the main differences are in how sustainable and socially convenient each pattern is for a given lifestyle.

What Breaks a Fast?

Breaks a fast: any caloric food or drink. Milk or cream in coffee. Fruit juice. Alcohol. Energy drinks with calories. Does NOT break a fast: water. Plain black coffee or tea (no milk, no sugar). Sparkling water. Electrolyte drinks with zero calories. Plain herbal tea. Black coffee in particular does not break a fast and may support fasting by reducing hunger. Chewing gum: technically zero calories but insulin response may be triggered in some people. Medications: most medications are fine to take during a fast, but some specifically require food to avoid stomach upset or to aid absorption — check with a pharmacist if unsure.

What do I need to know about Evidence for Intermittent Fasting?

Weight loss: IF produces similar weight loss to continuous calorie restriction when total calories are matched — the advantage is that some people find it easier to restrict calories within a compressed window. Metabolic benefits: some evidence for improved insulin sensitivity, reduced fasting insulin, and autophagy (cellular repair) during extended fasting. Conflicting evidence: some studies show muscle loss risk with extended fasting without adequate protein. Recent research suggests that the timing of eating may matter less than the total calorie deficit achieved, and that intermittent fasting works primarily by making that deficit easier to sustain for some people, rather than through any unique metabolic effect.

What should I know about Practical Fasting Tips?

Starting out: begin with a 12-hour fast (e.g. 8pm to 8am) — this is the baseline most people already achieve naturally. Gradually extend to 14 hours, then 16. Breaking the fast: break with a protein-rich meal to maximise satiety through the eating window. Coffee or tea (black) in the morning significantly reduces hunger and supports extending the fast comfortably. Electrolytes: extended fasts can deplete sodium and potassium. A pinch of salt in water or a zero-calorie electrolyte supplement supports appetite control without breaking the fast in the way food does.