We define fasting as a 'catch all' term for purposely:
- Skipping some type of (previously 'normal') eating occasions.
- Restricting some type of food group throughout the course of a day, week, or month
- Or maintaining a shortened window of time in your day where you consume calories and a longer period of time in your day with no calorie intake.
There are a variety of suggested health and performance related benefits which include weight loss, blood sugar control, better fat burning, reductions in long term disease-risk, improved mental clarity, and potential to increase healthspan and longevity. Here we discuss most established methods of fasting plus tips for implementing fasting successfully.
Methods of Fasting
Shortened Eating Window
Shortened eating windows, also known as time-restricted feeding, are when you keep all of your daily food intake to a window of 8-12 hours/day. Water is fine outside of this window, as it’s really more about caloric intake.
Range: 12 hrs is likely fine for already healthy people, but insulin resistant and overweight people may need to squeeze that eating window down to 8-10 hrs for best effect. Anecdotally, males and females may respond differently to shortened eating windows; females may respond better to a longer eating window, for example 10-12 h of eating rather than 8-10 h.
Rule of thumb: Eat while the sun is out. Try and consume most of your food when you can see the sun in the sky.
Window timing: Earlier hours (e.g. 8 or 9 am to 5 or 6 pm) are generally better than later hours (e.g. noon to 8 pm) but find what works for you in your life and aim to maintain a consistent eating window. Eating in that window most of the time may be good enough! Following this routine 5 days/wk should give you most of the benefit, while still allowing you to eat a bit later on weekends or other times you want to bend your rules some. Generally, stay as consistent as you can.