Lurisia Dale wrote:

>Well, you are right that the jury is still out about
>wheather or not long-termed ketosis is unhealthy or
>not.  However, here is good reason to avoid them
>(taken from "Burn the Fat, Feed the Muscle" by Tom
>Venuto):
>
>"Whether or not ketogenic diets are unhealthy is
>uncertain, but the real reason you
>should avoid them is because ketosis is not a
>requirement to burn fat.
>
Logically, the move from "It's not necessary to be in ketosis to burn
fat" to "there is good reason to avoid ketogenic diets" is weak. I agree
that it's not *necessary* to be in ketosis to burn fat, but that doesn't
address the question of whether there might be an advantage to doing so.

Here's something to consider. When not in ketosis, a gram of fat supples
about 9 kcals of energy. The conversion of that gram of fat requires
about 2 kcals of overhead, so that 7 kcals of utilizable energy remain.
This means that if your cells need 90 kcals of energy in a certain
interval of time, when you're not in ketosis they will burn about 10g of
fat to get it. If you are in ketosis, however, those 10g will only
deliver 70 kcals. To get the remaining 20 kcals that are needed, 3 more
grams of fat must be burned (almost). At first glance, that may not
sound like much, but for a person aiming to burn fat, it is very good
news. It means that when in ketosis he or she will have to burn almost
30% more fat to get the same energy yield that would occur when not in
ketosis.

> Only a calorie
>deficit is necessary to burn fat.
>

Maybe, but the relevant question is, what is the best way to maximize
fat burning and minimize muscle loss? Unfortunately, this question
hasn't been directly studied as many times as it should be, but the
studies that have been done indicate that the ratio of fat to muscle
lost, with a given caloric deficit, is inversely correlated with the
amount of carbohydrate in the diet, right down to the ketogenic level.
Charlotte Young's classic study in 1970 showed this very clearly, and
hasn't been contradicted yet.

>Ketogenic diets are
>extremely strict and nutritionally
>unbalanced. They are what you could call “extreme
>measures.”
>
>
Strict, yes. Nutritionally unbalanced, not necessarily. You can get all
your nutrients and stay in ketosis.

>It’s simply not necessary to remove all your
>carbohydrates or go into ketosis to
>accelerate fat loss. A moderate reduction in
>carbohydrates is often all it takes to help to
>control blood sugar and insulin better.
>
I agree. Sometimes this is all that is necessary. But as I've pointed
out, ketosis increases the demand for fat to burn by reducing its actual
energy yield, and for someone interested in losing weight that's an
advantage.

>Again, I never said anything against this.  I'm simply
>arguing against the (I think obviously wrong)
>advice to cut fruit and vegetables as a way to reduce
>carbs in general.
>
A further point is that weight loss is a temporary process, after which
one needs to find some sort of equilibrium. Some may prefer to remain in
ketosis, and do so. Others may prefer to reintroduce more fruits and
veggies into their diet. Of course, when they exit ketosis they must
once again burn 9 kcals for every gram of fat, so even if total intake
calories remain the same, they may find themselves gaining weight. For
this reason, the reintroduction of carbs would need to be accompanied by
some net decrease in calories consumed. This, by the way, is a criticism
I have of the Atkins concept of the "critical carbohydrate level", or
maximum amount of carbs one can tolerate without gaining weight. It's
not that simple, because when you exit ketosis other things change
besides your carb intake.

Todd Moody
[log in to unmask]