Intermittent Fasting & Calorie Restriction

Intermittent Fasting & Calorie Restriction

Introduction A recent UK TV programme (Monday 6th August 2012) has generated much interest about Calorie Restriction and Intermittent Fasting. The programme was a Horizon documentary, by Michael Mosley, called "Eat, Fast and Live Longer"[1] (The comma is very important!) The programme won't be on BBC iplayer for ever and people outside the UK can't get iplayer, so let's hope YouTube copies stay up for a while[2]. Other people have posted the programme in parts on YouTube so do try putting in the programme title if the links in the reference notes no longer work. Quick definitions Let's just differentiate between the two terms before we go any further: Calorie Restriction (CR) is long term restriction of calories below that needed on a daily basis by a person. As a general rule, CR involves an approximate 30% calorie deficit from the daily requirement. Intermittent Fasting (IF) should be, as the name suggests, fasting (eating nothing) for periods of time every now and again. However, Intermittent Fasting has come to mean many different things. Three things can vary: 1) Fasting does not necessarily mean eating nothing (drinking only water). Fasting is now taken to mean either eating nothing or eating substantially less than the recommended intake (25% of the recommended daily calorie intake serves as a common guide). 2) The length of time for which IF is undertaken can vary. Some regimes have a 3-5 day literal fast (water only - or a cup-a-soup, as we will see). Other options include fasting/eating little every other day; or doing this every few days or a couple of days a week and so on. 3) The frequency with which IF is done is the final variant. This is driven to an extent by (2) - an every other day restriction is obviously repeated every other day. However someone can choose to fast for between one and a few days every week, every month, every quarter or as desired. The permutations of 1, 2 and 3 make for numerous options available to people interested in Intermittent Fasting. Should anyone choose to do IF, they may be well advised to develop their own plan, taking the option most likely to work for them from fasting vs. eating little, how long the fast will be and how often it will be undertaken. Programme Synopsis Just in case you can't see the Horizon programme, or if you don't have an hour to spare - here's a synopsis of the documentary. The synopsis also serves as an excellent introduction to the whole topic of Calorie Restriction and Intermittent Fasting - Mosley has gone to the leading institutions and met the key researchers in these fields and this is a great place to start:

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