The FastDay Forum

http://www.scientificamerican.com/artic ... thier-life

Interesting read - not sure if there's anything new here but one of the comments by '6. terryb15d' is startling as he suggests " Intermident (sic) fasting seems like a pretty bad idea in light of this study."

This is the study he's referring to:
http://www.sciencedirect.com/science/ar ... 4911004473

and this is the Abstract

"Abstract
Calorie restriction is a dietary intervention known to improve redox state, glucose tolerance, and animal life span. Other interventions have been adopted as study models for caloric restriction, including nonsupplemented food restriction and intermittent, every-other-day feedings. We compared the short- and long-term effects of these interventions to ad libitum protocols and found that, although all restricted diets decrease body weight, intermittent feeding did not decrease intra-abdominal adiposity. Short-term calorie restriction and intermittent feeding presented similar results relative to glucose tolerance. Surprisingly, long-term intermittent feeding promoted glucose intolerance, without a loss in insulin receptor phosphorylation. Intermittent feeding substantially increased insulin receptor nitration in both intra-abdominal adipose tissue and muscle, a modification associated with receptor inactivation. All restricted diets enhanced nitric oxide synthase levels in the insulin-responsive adipose tissue and skeletal muscle. However, whereas calorie restriction improved tissue redox state, food restriction and intermittent feedings did not. In fact, long-term intermittent feeding resulted in largely enhanced tissue release of oxidants. Overall, our results show that restricted diets are significantly different in their effects on glucose tolerance and redox state when adopted long-term. Furthermore, we show that intermittent feeding can lead to oxidative insulin receptor inactivation and glucose intolerance."


HUGE sigh from me. Back to the drawing board?

Really interesting to read both sides of the argument. I expect that we'll see a lot more debates like this as IF attracts more publicity, which can only be a good thing.
I think we just have to be our own 'lab rats' and make our own decisions about whether this works for us or not.
For me, even if it just means I've found a way to lose weight and keep it off, I'll be happy. Any other health benefits will then just be the icing on the cake, so unless someone can categorically prove that IF can have damaging effects, I'm going to be continuing.

Totally agree....healthy debate and research is the only way forward ...what i fear is an onslaught of unhealthy debate and research backed by a multi billion pound diet industry .....they are highly unlikely to let go of such a profitable industry without shouting?....take a look at who backs a lot of research in America ...the major players???...they can afford to!!...and statistics and facts can be tweaked to suit most arguments depending on what angle you are coming from.
Is IF anymore or less dangerous to my health than obesity?
Will IF screw with my blood sugars any more than I had with my unhealthy eating habits?
Is IF anymore unhealthy for my body than the hundreds/thousands of 'diet' shakes bars and products that I have spent the last 30 years eating??
All I can tell you about IF (and I am not a scientist) is that since starting it, I am steadily shedding the pounds and feel more energetic and healthier than I have in a long time.
For me that is enough at the moment !

[carorees]

Since most of the IF studies have been based on ADF in rats, whereas most of us are looking at, in the long term, only fasting for 1 or 2 days a week and since a day to us is a lot shorter in terms of our lifespan than it is to a rat, I don't think I'm too worried. (I did post about why you have to be careful extrapolating from rat studies to us the other day). Of course the same applies to extrapolating the positives as well as the negatives so wee can't say that fasting will increase our lifespan but losing weight if not already a healthy weight will definitely improve our chances of a healthy old age so for that reason, I'm in!

Thanks Marlene for posting. This is a study in rats. It would be great if someone could explain what the authors are saying in words of one syllable for us non-scientists?

[carorees]

Rats fed every other day for 6 months (so the equivalent of a human fed once in 10 days for 15 years) resulted in insulin resistance and free radical production (that's the ADF protocol) whereas rats who ate their daily ration of reduced calorie chow in a period of 5 hours (which is what rats on a CR protocol do) showed improved glucose tolerance and reduced free radicals (this is the equivalent of us fasting for 3 days out of 4). Neither protocol can be translated to humans. The metabolic process of a rat are about 6-10 times faster than a human and rats lose 10% of their body weight in 24 hours without food whereas humans take 10 days. So ADF rats are effectively starving and gorging.

Rats fed every other day for 6 months (so the equivalent of a human fed once in 10 days for 15 years) resulted in insulin resistance and free radical production (that's the ADF protocol) whereas rats who ate their daily ration of reduced calorie chow in a period of 5 hours (which is what rats on a CR protocol do) showed improved glucose tolerance and reduced free radicals (this is the equivalent of us fasting for 3 days out of 4). Neither protocol can be translated to humans. The metabolic process of a rat are about 6-10 times faster than a human and rats lose 10% of their body weight in 24 hours without food whereas humans take 10 days. So ADF rats are effectively starving and gorging.

So, then, what's the point in studying rats at all if, as you say Caroline, 'Neither protocol can be translated to humans'? If this study has no real relevance to understanding IF and CR in humans, why undertake it in the first place (unless, of course, you have nothing better to spend your research grant on) and, secondly, why bother referring to it in a discussion on the efficacy of IF in humans? It's absolutely nonsensical to me and counter-productive - am I being dim?

Testing on mice and rats acts as a test of a concept - for example if calorie reduction in animals prolongs their life then it suggests the same thing is worth trying in people - the CALERIE trial for example.

If there was no effect on the lifespan of the animals, there's nothing to suggest there might be in humans.

I don't agree that rats on CR are necessarily feeding and gorging, trials with rats held at controlled weight use the same feeding protocol (fed once a day and uneaten food removed) and it's common to feed lab animals on Friday with their whole weekends food.

[carorees]

I guess it depends on the degree of CR as to whether they gorge or not! However, I agree it is important to understand that the studies in rats are aimed at giving a pointer as to what areas of research should be taken forward. Clearly the detrimental effects should not be forgotten but, as with the beneficial effects, we can't actually know for years what effect intermittent fasting will have in humans.

The rats on a CR diet, if they end up without any food for a few hours each day, are probably nearer to our situation than the ADF rats. The human ADF studies are nearer to our situation than any rat study. No-one has yet studied what we are doing so we just have to make an informed guess as to whether the benefits outweigh the risks. As being overweight is a massive health problem, I feel certain that in the short-term the benefits will outweigh the risks for people who are overweight. As far as I know, studies of people to undertake religious fasting have yet to show any problems with glucose intolerance, cardiac problems etc. Have you spotted any, Phil? We should certainly keep our eyes peeled for such studies!

Probably not a lot of research done on IF over the last several decades because there is not a lot of money to be made on people fasting. Much more money to be made treating people for diabetes and heart disease. The food industry markets junk food to people to make them sick and dependent on the healthcare industry by the time they are in their 50s.

However, whereas calorie restriction improved tissue redox state, food restriction and intermittent feedings did not.

This part confuses me, what the difference between calorie restriction and food restriction? The abstract is vague in that matter, perhaps the actual article says? (I'm not paying $32 to find out lol) So at this point I assume calorie restriction means just an overall such as sticking to 1200 calories no matter the food, and food restriction means cutting certain foods out of your diet. My thinking is that calorie restriction, despite what they claim is a better alternative, is not sustainable in the long run. I would rather take the benefits of 5:2 even if they aren't as great, at least it's something healthier than doing nothing (or trying cal restriction only to gain all back later.)

Nodakmom, I agree it is not very clear. My reading is that they are comparing 3 different feeding regimes for the rats:

1. 'calorie restriction' with (implied) additional dietary supplements
2. non-supplemented calorie restriction (which they call 'food restriction')
3. intermittent feedings (what we call ADF, although as this is applied to rats it isn't necessarily comparable with human ADF)