Question about ketosis

[Northlondo]

Is some degree of ketosis normal in any calorie reduced diet
or is it just 'normal' in a low-carb type diet?

I ask because it seems that ketones are a by-product of
burning fat and isn't that the aim of ANY diet?

Grateful for any references

TIA

[Mikev]

"Northlondon" <a@b.c> wrote in message
news:y8mDd.61505$Z7.54704@fe2.news.blueyonder.co.uk...
> Is some degree of ketosis normal in any calorie reduced diet
> or is it just 'normal' in a low-carb type diet?
>
> I ask because it seems that ketones are a by-product of
> burning fat and isn't that the aim of ANY diet?
>
> Grateful for any references
>
> TIA
>
It is normal to the extent that starvation can occur in
humans. For example in seasonal periods of starvation or near
starvation, during which pre-farming humans lived on their
bodyfat and proteins. Very low carb diets simulate this
condition, but are said to minimize the amount of muscle loss
because dietary protein levels are maintained. Eating
excessive calories of protein will result in gluconeogenesis
in the liver,(conversion of body or dietary protein to
glucose), or fat, will end normal ketosis. Ketosis supplies
most of its body fuel needs except for a percentage (25%) of
brains supply which must be furnished as glucose by the liver
(gluconeogenesis). Obviously you can starve on any diet if you
do it hard. Dieting with ketosis is said not to be unhealthy
unless you have pre-existing kidney disease.

If you are interested in doing a bit of digging, you may find
this site helpful:
http://snowwhite.med.upenn.edu/lewis/metabolism.htm

MikeV (Noted non expert.)

[Mmu]

The ammount of ketosis produced depends on the carbohydrate
intake - the less carbohydrates, the higher your level on
ketone bodies.

It is normal in regular starvation (ie. no food at all) and
typical for low-carb diets.

Body fat reduction also happens without raising the
production of keto-bodies in such a manner of course- in
normal low fat diets.

Good references are the textbooks (Streyer et al., Elmadfa et.
al, Biesalski et al,..)- probably contain way too much
off-topic info though.

"Northlondon" <a@b.c> schrieb im Newsbeitrag
news:y8mDd.61505$Z7.54704@fe2.news.blueyonder.co.uk...
> Is some degree of ketosis normal in any calorie reduced diet
> or is it just 'normal' in a low-carb type diet?
>
> I ask because it seems that ketones are a by-product of
> burning fat and isn't that the aim of ANY diet?
>
> Grateful for any references
>
> TIA

[Northlondo]

Thank you (both), but I'm still a tad puzzled.

The nub of my question is wrapped up in the bit where you say

"Body fat reduction also happens without raising the
production of keto-bodies in such a manner of course- in
normal low fat diets."

Where does the body-fat go under these circumstances if it
isn't burned for energy (thus producing ketones).

Consider an average man consuming a 'normal balanced diet'
yielding 2,500Kcals per day. If he reduces the quantity of
daily food intake to 2,000Kcals without altering his dietary
mix then I am told he will lose around a pound of body fat per
week. Presumably this fat is burned to make up the 500Kcal per
day energy deficit. Will he see any trace of urinary ketones?
If not where does the fat go?

TIA

"MMu" <brilhasti@gmx.net> wrote in message
news:41de7534$0$10578$3b214f66@usenet.univie.ac.at...
> The ammount of ketosis produced depends on the carbohydrate
> intake - the less carbohydrates, the higher your level on
> ketone bodies.
>
> It is normal in regular starvation (ie. no food at all) and
> typical for low-carb diets.
>
> Body fat reduction also happens without raising the
> production of keto-bodies in such a manner of course- in
> normal low fat diets.
>
> Good references are the textbooks (Streyer et al., Elmadfa
> et. al, Biesalski et al,..)- probably contain way too much
> off-topic info though.
>
> "Northlondon" <a@b.c> schrieb im Newsbeitrag
> news:y8mDd.61505$Z7.54704@fe2.news.blueyonder.co.uk...
>> Is some degree of ketosis normal in any calorie reduced
>> diet or is it just 'normal' in a low-carb type diet?
>>
>> I ask because it seems that ketones are a by-product of
>> burning fat and isn't that the aim of ANY diet?
>>
>> Grateful for any references
>>
>> TIA
>

[Mikev]

"Northlondon" <a@b.c> wrote in message
news:zjwDd.62575$48.1959@fe1.news.blueyonder.co.uk...
> Thank you (both), but I'm still a tad puzzled.
>
>>SNIP
> Where does the body-fat go under these circumstances if it
> isn't burned for energy (thus producing ketones). SNIP If
> not where does the fat go?
>
>
> TIA
>
> "MMu" <brilhasti@gmx.net> wrote in message
> news:41de7534$0$10578$3b214f66@usenet.univie.ac.at...
>> The ammount of ketosis produced depends on the carbohydrate
>> intake - the less carbohydrates, the higher your level on
>> ketone bodies.

>
I think the key you are looking for is whether or not stored
liver glycogen has been depleted. Normal lipolysis (fat
burning) directly involves fatty acids, and occurs in cells
containing mitochondria. Large FA molecules cannot access the
brain and certain other tissues. Beyond this point, in the
absence of dietary carbohydrates, glucose and ketones must be
produced in the liver. (neoglucogenesis from proteins, ketosis
from fatty acids from adipose.) You can see then that ketosis
is only used in perceived emergency. I believe you may also
see ketones generated by athletes such as marathon runners who
place very heavy demands on lipolysis.

From Prof Mitch Lewis's (Univ. Pennsylvania) Intermediary
Metabolism Course Handouts:
http://snowwhite.med.upenn.edu/lewis/metabolism.htm

From: Handout 14: Fatty Acid Oxidation

"Fatty acids are oxidized by all tissues with the exception of
tissues with no or only few mitochondria (red cells and
glycolytic muscle fibers) and of the brain, which, although
full of mitochondria, cannot import long chain fatty acids
(with16-18 carbons the fatty acids of adipose tissues are
long). Nevertheless, during starvation (i.e. a number of days
without food), even the brain can benefit indirectly from the
fatty acid oxidation in the liver by using a fatty acid
oxidation by-product, keto acids, to partially substitute for
glucose as energy source."

From: Handout 15: Ketoacids.

"The blood ketone level is permanently elevated during a
ketogenic diet, consisting of fat + proteins without
carbohydrates (cf handout
10), where the glucose supply depends entirely on
gluconeogenesis from the ingested proteins. The waste of
calories due to the ketonuria associated with this diet
**maybe** relevant to its slimming effect (Atkins diet). As
mentioned above, the plasma ketone level tops out at 5mM
during long term starvation. An increase above 5mM, which
would represent ketoacidosis, is prevented by feedback
inhibition in the healthy individual (Fig.8).

It is exerted by insulin release (ie feedback *mv*) from the
ß-cells in response to the elevated ketone concentrations (cf
handout 10). The amount of insulin released, however, is
small, just enough to adjust the I/G ratio to a value that
maintains the concentration of the ketoacids at 5 mM.

Insulin inhibits ketone synthesis at two points: first it
lowers the supply ofthe substrate, acetylCoA, by reducing
fatty acid oxidation, curtailing both, fatty acid release from
the adipose and fatty acid entry into liver mitochondria.
Second, it lowers the transcription of HMGCoA synthase."

MikeV

** While this may be a part of the so called metabolic
advantage, these effects are believed to be relatively small,
and are easily overwhemed by excess calories** HTH mike