Fast-5 was created by Dr Bert Herring while working at the National Institutes of Health in the USA and claims to mimic the eating schedule of ancient humans who ate without benefit of food storage or refrigeration. It is based on a 5-hour eating window (so at FastDay we call this 19:5 fasting), taken whenever you wish, but generally involves keeping to a normal-timed dinner combined with a late lunch (e.g. eating between 2pm and 7pm). Because of the very restricted eating window, most people should lose weight using this system, but the short eating window may make it harder to fit into daily life.
Learn more about what and when to eat
How do I do it?
Fast days: restrict your eating to a 5-hour time period.
Non-fast days: eat whatever and whenever you like.
FastDay says: it is best to start with a longer eating window and cut down gradually until you get to 5 hours. Although the creator of the diet does not suggest any non-fast days, we think that fasting every day for long periods may be too stressful for the body. Scheduling some non-fast days may be wise.
Is this the one for you? Jump straight to Getting started: your first fasts
Why I like 19:5
Forum member barbarita says: “I started out on 5:2 because it was the first type of IF I encountered. I started it because of the health benefits but was pleased to lose weight also. From the beginning I didn’t bother with calories, eating nothing on the fast days and going by appetite on other days. When I came across Fast-5 I recognized I was really in tune with it. Eat nothing for 19 hours then eat as you please in the remaining five. No rules, no BMR, no TDEE no recipe books, no counting, no weighing (except me!). No books except a free e-book. Freedom from everything except the clock.”
Read why other forum members chose their fasting method
The Warrior Diet created by Ori Hofmekler is essentially the same as Fast-5 but focuses on having just one large meal a day in the evening which is allowed to last for as long as 4 hours (i.e., 20:4 fasting). Like Leangains it is aimed at people wishing to do muscle building and hence also includes nutritional guidelines.