Question about ketosis

"Northlondon" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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.)

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" <[email hidden]> schrieb im Newsbeitrag
news:[email hidden]...

Quoted message said:

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

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" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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" <[email hidden]> schrieb im Newsbeitrag
news:[email hidden]...

Quoted message said:

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

"Northlondon" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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

Quoted message said:

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" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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

Quoted message said:

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