Here is an interesting abstract exploring fatty acid synthesis on
low fat diets.  It is located at
http://www.diabetes.org/ada/res1.html.

My reading is that it seems to confirms results previously posted
to this list: a higher proportion of CHO is synthesized to fatty
acids the higher is the ratio of CHO to fat in the diet.  The
subjects in this case were insulin-resistant; there were no normals
in the study.

If the fatty acid synthesis of these insulin resistant subjects
exceeds that of normals, then this is suggestive of a mechanism for
a "thrifty gene".  The abstract fails to separate an increase in the
RATE of fatty acid synthesis from the LEVEL accumulated in blood
trigyceride.  It is clear the rate increased and it seems the level
as well.

Abstract follows:

Clinical Research Grant

Sensitivity to Carbohydrate-Induced Fatty Acid Synthesis in the
Insulin Resistance Syndrome

Lisa Cooper Hudgins, MD
New York, NY

Summary of Results:
In the first year, using solid food diets composed of commonly
consumed foods, my project explored the effects of a reduction in
the amount of dietary fat and an increase in the amount of
carbohydrate on the body's own production of fat in normal and
obese, insulin-resistant volunteers. In seven normal volunteers
studied for one month in the controlled environment of the
Rockefeller Clinical Research Center, we found that when the dietary
carbohydrate was high in simple sugars and low in complex
carbohydrate, the body converted the carbohydrate to fat when 30% of
calories were fat, and even more when 10% of calories were fat.
When fat production increased, the newly formed saturated (animal)
fat accumulated in the blood triglyceride with potential adverse
effects on heart disease and diabetes. An important finding was that
there was no change in body weight or metabolic rate between the
high fat and low fat diets. Surprisingly, two obese subjects with
high fasting insulins and other characteristics of the insulin
resistance syndrome showed less, rather than the predicted greater,
fat production on the two diets. More subjects need to be studied to
confirm this finding that may be a consequence of decreased
responsiveness to insulin.