Intermittent Fasting Calculator

Intermittent fasting is not a diet in the traditional sense — it is a meal timing strategy. The core principle is simple: restrict eating to a defined window and fast for the remainder. The 16:8 protocol (16 hours fasting, 8 hours eating) is the entry point for most people, typically implemented by skipping breakfast and having the first meal at noon. More aggressive protocols like 20:4 or OMAD are favored by experienced practitioners seeking deeper metabolic effects.

The weight loss benefits of IF stem primarily from reduced eating opportunities. A compressed eating window naturally limits calorie intake for most people, without the need to count every gram. This psychological simplification is its main advantage over conventional calorie restriction, which requires sustained willpower across all waking hours. Studies comparing IF to equivalent calorie-matched continuous restriction generally show similar body composition outcomes.

Beyond weight loss, research supports IF for improvements in insulin sensitivity, blood pressure, inflammatory markers, and cellular autophagy. The 5:2 variant — eating normally five days and restricting to 500 calories on two non-consecutive days — provides a different structure that some find easier to maintain long-term. Whichever protocol you choose, protein intake on eating days should remain high (0.7–1.0g/lb body weight) to preserve lean mass during the fasting-induced caloric restriction.