is an intentional reduction of your daily or weekly caloric intake. It works on a “calories in, calories out” basis, so that your energy output is greater than your energy input, which forces your body to burn stored fat for energy.
you may have heard of intermittent fasting, does not necessarily require caloric restrictions. It simply involves not eating for a given amount of time, and then eating in a limited period called a compressed window.
You don’t eat less; you eat less often
Why is it important to make this distinction?
Many lean, highly active people that engage in frequent 12 – 16 hour intermittent fasts, regular 24 hour fasts or 3 – 5 day fasts, and then they encounter thyroid downregulation, hormone depletion, low energy, and poor sleep because they are attempting to marry caloric restriction-based fasting with an extremely active, calorie-decimating lifestyle and a body that doesn’t have a ton of energy stores to tap into.
If you are overweight, obese, sedentary, or in need of giving your gut a serious break from calories, fasting can give you the benefits of restricting calories without actually restricting calories.
Common types of fasts
12 -12 finish eating at 6pm at night and then have breakfast after 6pm
16 – 8 (fast for 16 hours and have an 8 our eating window). This fast can be too much for some women as they can be capable of causing hormonal imbalance and metabolic dysfunction.
For some a longer fast is not always more.
Be educated when it comes to your metabolic health and hormones.
source: Ben Greenfield