Intermittent fasting has gained popularity as a weight loss strategy, but its effectiveness depends not only on the duration of fasting but also on when meals are consumed. Many people follow the 16/8 method, which involves eating within an 8-hour window and fasting for the remaining 16 hours of the day. However, small snacks, sweetened coffee, and frequent "bites" can interfere with the fasting period, reducing its potential benefits. The actual advantages—such as improved metabolism or cellular repair—depend on how strictly the fasting window is maintained. According to Javier Fernández Ligero, a Spanish nutritionist and pharmacist, the success of intermittent fasting hinges on understanding how the body uses energy during fasting. He explains that after about 12 hours of not eating, the body begins to deplete its glycogen stores. Glycogen is a form of stored energy found in the liver and muscles, acting as the body’s primary energy source when food is not available. As the fast continues, typically around 14 to 16 hours, the body initiates a process called autophagy. This is a cellular "clean-up" mechanism where the body removes damaged cells and recycles their components, potentially offering health benefits such as improved cellular function and longevity. Fernández Ligero emphasizes that this process is more likely to occur when fasting is done consistently and with minimal food intake during the fasting window. To maximize the benefits of intermittent fasting, Fernández Ligero suggests aiming for at least 12 hours of fasting daily, especially on days when physical activity is low. He provides a kind of hourly guide to help people structure their eating and fasting periods effectively. For more detailed advice, readers can refer to the full article on Doctissimo.