The FastDay Forum

Hi, all,

I've been doing 5:2 for almost 6 weeks now & it seems to be working for me (lost an inch from the waist and 6lbs), but I'm starting to get a bit confused about the fasting aspects.

The diet seems to work on 2 levels: at its simplest it's a relatively palatable way of reducing overall calorie intake. For me, this means reducing my intake from about 2500 to 600 a day, twice a week. This gives me a calorie deficit of about 3800 a week, which equates to my weight loss of just over 1lb / week. This is fine & I'm looking forward to being able to continue long enough to make a serious impact on my weight (currently just under 16st), but the book promises more...

It's these extra benefits that I'm trying to take advantage of - it would be really good to increase my BDNF & reduce the risk of early dementia, and also get the benefits of reduced IGF-1 etc. It seems that these benefits are triggered by (amongst other things) the low levels of insulin that develop after a period of fasting - but how long do I need to fast for the changes to kick in?

MM seems to suggest that a couple of 12 hour fasts in a 24 hour period are good enough (page 75 of the Fast Diet book). On the other hand, Todd Becker (http://gettingstronger.org) and other advocates of the fast-5 diet (http://www.fast-5.com) say that you need a clear 19-hour fast to see the benefits.

So who's right? Is it a sliding scale with more benefits accruing the longer I fast, and if so what's the minimum fast period for them to be worthwhile?

Mike

[Moogie]

I'm no scientist but from what I've read, the longer without food the more the benefits. That said, MM had his blood test results improve noticably from his method of 2x12 hour fasts.

Personally I find it easier to go 24 hours without food, then have my 500 cal fasting dinner which is then followed by another 12-16 hours fasting until breakfast on my feed day (sometimes I don't feel like breakfast until midday!).

[carorees]

No one knows I'm afraid. The different fasting experts all say something different. However, perhaps it is better to think about when detrimental effects of fasting might occur such as raised cortisol, reduced thyroid function? Again this is unclear but my guess is that the best balance between positives and negatives is likely to be around the 24 hour mark, though of course there will be considerable variation between people. Until there are more studies we're all guessing!