Intermittent Fasting Calculator

Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. It does not prescribe which foods to eat but when to eat them. Common protocols include 16:8 (fasting for 16 hours, eating within an 8-hour window), 5:2 (eating normally 5 days per week, restricting to around 500 calories on 2 non-consecutive days), and alternate-day fasting. IF has gained interest for its potential effects on weight, insulin sensitivity, and metabolic health.

Current research suggests that when total calorie intake is matched, IF produces similar weight and fat loss to continuous calorie restriction. However, some people find IF easier to adhere to because it simplifies meal planning. During the fasting window, insulin levels fall and fat oxidation increases; this metabolic switching is one proposed mechanism for its benefits. IF is not superior for everyone and may not be suitable for those with a history of eating disorders or certain medical conditions.

Yes, plain black coffee and unsweetened tea are generally considered acceptable during the fasting window, as they contain negligible calories and do not meaningfully raise insulin levels. Adding milk, cream, sugar, or flavoured syrups breaks the fast by introducing calories. Sparkling water, still water, and black coffee or tea are the most commonly recommended zero-calorie beverages during fasting periods.