Does a fasting window start the minute you take your last bite of food?

According to Andrew Huberman, the fasting window does not begin immediately after taking the last bite or sip of food. This is because the body continues to digest food that remains in the stomach and intestines, and this process can take several hours depending on the size and content of the meal. Larger meals and those high in fats take longer to digest, thus delaying the transition into a fasted state 1.

Therefore, while you might start your fast on a timer or app right after your last bite, your body may not actually be in a biological fasted state for some hours. It's important to consider these aspects when planning fasting schedules, as the body's transition from a fed to a fasted state depends on digestive processes, not just the cessation of eating 2 3.