Potential sodium issues with QOD fasting

[Guest guest]

" Do we really have concerns that going without food for one day, or

two at the most, might cause electrolyte problems? If so then that

is news to me and I would be interested to see some data/information

about it. If anyone has a reference at their fingertips. " ?\

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Well with regard to sodium, there are a lot of data that it takes the

kidneys several days to adapt to a low-sodium intake:

Here's one:

http://hyper.ahajournals.org/cgi/content/full/30/5/1216

" Cumulative Sodium Balance

Twenty-four–hour urinary sodium output fell gradually, as expected,

during the first few days of dietary restriction. A new steady state,

during which sodium output again matched intake, generally was reached

by the fourth day, but time courses varied from 3 to 6 days " .

There are lots of others - most of these studies were done in the

course of experiments of putting people of a very low sodium diet for

testing purposes. The bottom line is this: Our kidneys are optimized

for a low sodium diet. In most places where we evolved, salt was

scarce. Salary comes from " salt " , showing how valuable salt was.

So we need less than 0.5 g/sodium per day, but we eat about 3-4 g/day.

The new diet gurus want us to restrict to 1.2-2 g/day, depending on

whom you read. Our kidneys adapt to this by pouring out all of this

salt that we eat, but if we suddenly stop eating it, it takes them 3-6

days to come back to " normal " and start conserving sodium. When the

kidneys lose sodium, they also lose water. This lowers the blood

volume, and a lower blood volume makes you feel bad.

Now whether this causes a problem for fasters in terms of feeling

poorly? No one has studied this, but my own experience suggests that

this is a major cause of feeling week and washed out during fasting.

The problem is, you find what you look for, and you look for what you

know. In the Heilbronn-Ravussin paper (Jan, AJCN), the patients

following a strict QOD fast felt " grumpy and irritable " , but there

were no recorded changes in blood pressure, or postural dizziness

(which might be expected if volume depletion due to salt loss was a

problem). So their data suggest that this is not a problem, but

again, unless a problem is specifically identified and looked for, it

is unlikely it will be found.

A Chinese saying? You find what you look for, and you look for what

you know. or was it Merrill Sossman, MD, a former chief of radiology

at the Bent Brigham Hospital, stated this well: " You see what

you look for and you look for what you know. "

http://www.jultrasoundmed.org/cgi/content/full/23/12/1543

My own experience is in dealing with patients on dialysis, where they

have no urine output. If you take off too much sodium and water, the

person will feel absolutely terrible - weak and washed out.

So the sodium issue is easily fixable. Potassium is sort of a sodium

antidote, and I don't think it's wise to simply take a salt tablet

during the OFF day. So in my approach I recommend taking in salted

vegetable juice (e.g., tomato juice or V8) or salted vegetable soups,

to provide not only sodium, but also potassium, magnesium, and other

minerals during the OFF day.

The problem is, potassium (K) recommended intakes are 4.7 g/day, and

Americans usually eat only about 2 g/day. So if you take no potassium

during your OFF days, even if you eat a " healthy " diet during your ON

days, you may have less than an optimum potassium intake.

All of this needs to be studied in a carefully controlled fashion. T

Relatively easy study to do, I would think.

More on the calcium issue later. The calcium issue is of great

interest, but with a time course of a decade or more, so it's a

different type of discussion. But after all, CR'ers and IF'ers are

thinking in terms of decades, aren't they? :-)