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Monday, May 7, 2012

Intermittent Fasters might be interested in this.

This is quite an old study, published in 1962, and it's in rats who are known to have greater DNL in adipose tissue.  This was a fairly short study, wherein rats were put on a 2 hr/day ad libitum eating schedule for one week.  Intake was 60% lower on day 1, but back up to 95% of normal ad libitum intake by the second day.  Thus the rats lost weight early on, but were back within 10% of their start weight by week's end.  

Essentially it appears that in short order with a switch to such a regime, adipose tissue storage and DNL in adipose tissue is upregulated considerably (10 fold).  Normally a 24 hr fasted rat will have depleted glycogen stores as some is burned along with fatty acids.  Rats adapted to this regime had full liver glycogen after the 24 hr fast indicating that they likely use fats preferentially for fuel.  

Interesting ... not sure what it means in humans.  But if something similar occurs, it could explain the insulin resistance many IF'ers seem to have, as non-oxidative glucose disposal -- e.g. glycogen synthesis -- is a major route of glucose disposal that is "defective" in IR states when reserves are high.  Especially with LC, if glycogen is spared and glycogenolysis doesn't provide blood glucose, gluconeogenesis would be upregulated. The combo with hepatic IR may well be the reason why IF'ers often have quite high fasting blood glucose.


Swede said...

IFers have a lot of insulin resistance? Where did you here this? And high fasting blood glucose?

Maybe its not the fasting but the fact that people with those conditions will try fasting as a way to improve health.

Evelyn aka CarbSane said...

I was a pretty dedicated IF'er for several months in 2009. One morning my FBS hit the low one-teens and it was alarming to me. On Jimmy's forum there were quite a few IF'ers at the time and there are some long IF threads there. It is not an uncommon complaint among IF'ing low carbers for FBS to rise. One woman was diagnosed prediabetic and the amount of rationalizing that goes on -- as to why elevated FBS is "normal" with IF, is astounding. The woman I'm thinking of was at a low weight for herself too and had been doing it for well over a year at the time.

Swede said...

IF + low carb = bad news

No one with poor blood sugar control should ever try fasting.

Sounds like the typical low carb crap! "This is normal because...I'm low carb and things are different..."

Lerner said...
This comment has been removed by the author.
Princess Dieter said...

My blood glucose improved, got lower and lower, starting at 99, as I did IF last year (and even exercised fasting), until I finally got into the mid 70s. But I didn't do low carb. I did moderate carb--as I cant' give up fruit :). I did it specifically for the improvement in insulin resistance that I heard about. It seemed to do fine by me. I still occasionally do it , but not as dedicatedly as I did spring and summer last year. Of course, I was also having some improvement in weight loss doing it, and that helps. Just adding my anecdote into the stew.

Lerner said...

Unrelated news:

May 6, "Eating for pleasure apparently has different effects on gastric hormones and neurotransmitter function than eating to live, Italian researchers found... No such increase was seen when, under the same conditions, the same volunteers were told to eat foods they didn't like but that had the same calorie content."

Swede said...

Sounds good. Once you can do IF, it is a great tool.

I have days where I eat most or all of my calories in a small window, maybe 6 hours or so. You can eat big and then be done with it!

James Krieger said...

There's a lot of different types of IF. The type of IF espoused by people like Martin Berkhan is going to be much different than some of the low carb IF stuff you see

ivat said...

Good luck to people who enjoy intermittent fasting; but I feel sorry for any food lover who feels that's the only way they can keep their weight down over the long term. I thought that would be my fate, but since I made target weight, my focus has been to find ways of eating regularly, eating well, and maintaining weight. That's why I read as much as I can about the ins and outs of how digestion works--in books and on sites such as yours. To my surprise, I've discovered strategies that work, on three meals a day and no calorie restriction (but also no stuffing). Intermittent fasting is not comfortable for most people and not necessary, in my opinion. For those who find it stimulating, fair enough; but as a weightloss or maintainance strategy, it borders, I venture to say, on an eating disorder.

Swede said...

"but since I made target weight, my focus has been to find ways of eating regularly, eating well, and maintaining weight"

Yup. Hard as it might be to believe, arriving at your goal allows more dietary freedom. Losing fat is in no way easy, but once its done you dont have to be as strict with your diet on a daily basis.

ivat said...

Inevitably, I think the weight-loss mindset is not entirely rational. Many people do extreme things to take off weight; they know some of the strategies they resort to aren't healthy or sustainable, but they want that weight off at all costs. I remember doing a couple of months of only one meal a day--a form of intermittent fasting, I suppose. I also did a couple of weeks of eating only every other day, because I felt I was stalling. But I knew it was madness, and in the back of my mind I was determined not to have to depend on such behaviours for life.

Honestly, though; if I'd known then what I know now about which foods do not induce weight gain, I could have taken the weight off while eating more than I did.

James Krieger said...

I'm not sure how one can classify IF as a borderline "eating disorder." There are many types of IF, and IF can involve regular eating too...just in a smaller window. Martin Berkhan's approach is an 8-hour feeding window and 16 hour fast...not really that far off from most people's 12 hour feeding windows. We're all IFers anyway since we don't eat for 8 hours each night while we sleep (well, at least most of us).

Sanjeev said...

play around with this

which we discussed here

I use the tool to get an idea of shapes and changes, not for absolute numbers.

On the right hand panel above the graph tick off "Advanced controls"

To the left of that, enter 3000 for "length of simulation" (tis is just to show very long term effects)

then above that input different sets of numbers for "First change" and "Second change" and be sure to set "Start change on day" for "second change" to 1500 or 2000

> arriving at your goal allows more dietary freedom

recipe for weight/fat loss disaster, IMHO.

If the diet WORKED, especially over let's 2 years, and keeps working, then the person, the diet and the lifestyle meshed. The best possible action would be to CHANGE NOTHING.

Sanjeev said...

Even with small changes, after the settling period when the system is at the new "stable" state, changing the parameters changes the results.

so there's no "stickiness" where one's reduced weight will refuse to change. You may be able to see some interesting dynamics if you initiate the second change on the active downside (instead of the stable end state) but that's

The only interpretation that makes sense of this fairly commonly repeated notion is that one diet down BELOW permanent goal weight then ease up on the diet, and hopefully the new higher weight is the permanent goal weight.

Sanjeev said...

> (instead of the stable end state) but that's

don't know why this got cut off ...

(instead of the stable end state) but that's not most people's' goal ... fiddling with weight loss dynamics to see interesting bouncing-around effects.

Unknown said...

Martin's approach imo is not meant for obese people, if you look at the photos on his site, most of them are pretty fit people who want to become leaner.

Given that they appear to be athletic, and that Martin does not favor LC, they are probably not LCing either.

Lean Gains is popular on a lot of low carb blogs but Martin refers to LCers as "The Taliban" so that's not what he has in mind.

Galina L. said...

Check the Hyperlipid blog on the subject of physiological insulin resistance. You can have higher fbs on LC.

Rob said...

Actually you are misinformed, martins protocol is essentially calorie/carb cyclying so on non-workout days, low carb and high fat then workout days, high carb and low fat. Protein usually stays the same on all days. However on rest days that doesn't mean it's zero carb or even less than 50g for example, it'll depend on the individual (same for fat amount).

Martin calls the fundamentalist variety "low carb talibans", re-read the article. He's not knocking low carb per se.

And he's had obese clients, see here:

Unknown said...

I read that and I didn't see the part where I was misinformed.

ivat said...

My doubts about intermittent fasting don't apply to people who enjoy it, feel stimulated by it, etc. I just feel it's a sorry strategy to have to adopt to keep weight at a particular maintenance level, especially if you enjoy meals. I do suspect that anyone who uses the up times to binge still has issues. I'm convinced there are other ways to maintain preferred weight than forcing oneself to go without food for spells.

David said...

I don't know how you came to the conclusion that LG is not meant for obese people, when there is a clear success story of an obese person. Are you painting the generalization out of your own opinion based on the pictures on the site or are you saying it as your own opinion formed from some perception that all obese people should follow LC diets or what?

rodeo said...

Ivat: So what your saying is that for those who fasting is good for it is good, but you have doubts about if fasting is good for those who fasting is bad for?

Ed Lee said...

Interesting, but I would postulate that the IF feeding pattern in rats might be closer to the periodic starvation response in humans. I have no idea how often rats normally eat, but I think I read somewhere that they have a much higher basal metabolic rate, so that particular feeding pattern might be more analagous to a human going a number of days without food, for example, and refeeding, rather than doing a daily IF regimen.

If so, it's interesting that the rat response is similar to the human fasting response which MAY BE INADVERTENTLY induced in some low carbers due to excessive carbohydrate reduction, as Jaminet addresses in his safe starch arguments.

Consider the patterns... the rats may be going into a pattern of periodic starvation. What do they do? They adapt by increasing insulin resistance in peripheral tissues, conserving limited glucose, presumably for nervous system tissues. Their glycogen doesnt get fully depleted overnight because of this induced insulin resistance. Adipose tissue gets upregulated... another energy conservation measure. This sounds a lot like the human fasting response. With respect to IF amongst the LC crowd... perhaps our glucose limitation is favoring a starvation response, and IF is only exacerbating the situation?

I was thinking that humans developed this IR response to starvation as an adaptation to ice age environments (I was going to reference her older piece, but when I searched, an update appeared..., with periodic feast/famine cycles, but the maybe this response is well evolved in mammals probably much further back in time?

No conclusions here... just random postulation from someone trying to decode their personal health.

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