What OP is referring to is intermittent fasting. In a 24 hour day, you don’t eat or fast for x # hours and then allow yourself a time window of y # hours where you are allowed to eat. In OP’s case, they are fasting for 20 hours and allow themselves a 4 hour time period per day where they can eat. It helps with a calorie deficit by limiting when you can eat, rather than mindless eating throughout the day. It can be a helpful tool for some.

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