Intermittent fasting involves cycling between eating and fasting periods, with no single required duration—the length depends on your chosen protocol. Common approaches range from 12 to 36 hours of fasting per day or per week. The most popular method, 16/8 intermittent fasting, involves a 16-hour daily fast followed by an 8-hour eating window. Other protocols include 5:2 (eating normally five days weekly, restricting calories two days), 24-hour fasts once or twice weekly, or eat-stop-eat approaches. Some people practice extended fasts of 24–48 hours less frequently. There's no universal "correct" fasting duration; effectiveness depends on your goals, lifestyle, and how your body responds. Research suggests benefits can occur with various fasting windows, though individual results vary. Beginners often start with shorter fasts (12–14 hours) and adjust based on hunger, energy levels, and results. It's important to maintain adequate nutrition during eating windows and stay hydrated during fasts. If you have existing health conditions, take medications, or are pregnant or breastfeeding, consult a healthcare provider before starting intermittent fasting, as certain fasting durations may not be appropriate for everyone.