The FastDay Forum

[carorees]

The idea that low blood sugar levels results in shakiness and unpleasant symptoms is widespread, particularly among people who have never tried fasting. As most of us know, these symptoms may be felt during the first fast or two but are not felt during subsequent fasts.

I came across a research study: http://www.ncbi.nlm.nih.gov/pubmed/17522614
which found that blood sugar levels do not dip below the normal range during a 24 hour fast in people who report "symptoms of hypoglycemia during episodes of food restriction".

I wonder if some of the symptoms are in fact due to increased ketones circulating rather than low blood sugar? Thoughts anyone?

"There were no differences between the groups in plasma glucose, cortisol, growth hormone (GH), insulin, beta-hydroxybutyrate (beta-OH) and lactate levels."

beta-OH is a ketone, so I think we can assume it isn't that.

This much earlier study (1991) looks at 'importance of insulin in subjective, cognitive, and hormonal responses to hypoglycemia in patients with IDDM'.

Could those symptoms (shakiness, headaches etc) be a sign of insulin resistance? Which might also explain why they tend to go away once we are established on the fast diet?

"Pronounced orthostatic hypotension
occurred by the second week and persisted
throughout the fasting period. The subject became
symptomatic after several days and was nearly
incapacitated by the postural hypotension after
33 days, requiring 20 to 30 minutes to go from
the supine to the upright position on rising in the
morning."

http://www.ncbi.nlm.nih.gov/pmc/article ... 7-0055.pdf 1982

As circulating glucose drops, liver glycogen needs to be converted back to glucose and released to replenish it. The hormone that signals this is cortisol, a stress hormone. I believe that in those of us with poorly working glucose metabolisms (i.e., most of us) there may be cortisol resistance, analogous to insulin and leptin resistance. The result is that it takes more cortisol to get the job done, and we feel edgy, shaky, etc. I'm hoping 5:2 corrects this quickly.

[carorees]

"There were no differences between the groups in plasma glucose, cortisol, growth hormone (GH), insulin, beta-hydroxybutyrate (beta-OH) and lactate levels."

beta-OH is a ketone, so I think we can assume it isn't that.

Oops! didn't spot that...speed reading!

I would think cortisol increases would be transient--enough to be felt but easy to miss on a panel, depending on when the blood was drawn.

Just came across this thread on the fasting connection site:
http://www.fastingconnection.com/forum/ ... nd-shaking

[carorees]

Interesting, particularly this bit:

1. Blood sugar drops. This holds for us habitual fasters also, but since we regularly make enzymes capable of converting fat to useful energy (ketones), these enzymes are "on standby" and can do the conversion on short notice. For those who haven't fasted for 2 weeks or more, the activation of these enzymes can take up to 3 days.

Interesting, I agree but I wonder if there's any research behind what he says.

[carorees]

Well there's a fair bit on metabolic inflexibility which is the body's inability to switch fuels, but I'm not sure about the 3 day thing which was the interesting bit for me. I'll see if I can find out.

"enzymes capable of converting fat to useful energy (ketones)" - Free fatty acids are utilised as energy by muscles, not convinced.

Before fasting I use to experience all kind of 'low blood sugar style" feelings if I didn't eat regularly. Bizarrely since fasting I haven't once - not once. The worst I get is a slight nausea feeling around midday and then again at about 4pm. It doesn't last more than 10 minutes and really isn't a big deal.

I also used to get migraines if I didn't eat properly and it was my biggest fear that the frequency would increase if I fasted. I haven't had a single one since starting. (Touches wood). I can only assume that there's a psychosomatic element to this or alternative my body responds very quickly to major changes... or I'm just the odd one out.
It helps that I'm now very much in tune with what hunger, appetite and greed all feel like and can therefore overcome each of them...

Incidentally, the slightly anxious/stressy/pumped up feelings I got in the first week or two have now completely gone - perhaps the comment above on cortisol resistance may be right. However, I now do get pronounced (i.e. very noticeable, but the effects only last 10-20 secs tops) orthostatic hypotension, especially on fast days but more generally as well - I'm off to the Doc's next week to check there's not something else involved but it's possible the loss of 12Kg weight in two months has been a little too much

James