Objective—To determine effects of dietary lipid and
protein on plasma lipoprotein and free fatty acid concentrations
and hepatic fatty acid synthesis during
weight gain and rapid weight loss in cats.
Animals—24 ovariohysterectomized cats.
Procedure—Cats were fed a high energy diet until
they gained 30% of their ideal body weight and then
randomly assigned to receive 1 of 4 weight reduction
diets (6 cats/diet) at 25% of maintenance energy
requirements. Diets contained a low or high quality
protein source and a lipid source deficient or sufficient
in long chain essential fatty acids. Plasma samples
and liver biopsy specimens were obtained before
and after weight gain and during and after weight loss
for determination of free fatty acid, triglyceride, and
lipoprotein concentrations. Synthesis of these substances
was measured by use of isotope enrichment.
Results—Plasma total cholesterol concentration and
concentration of lipoprotein fractions increased after
weight gain, compared with baseline values. Weight
loss resulted in a significant decrease in concentrations
of all lipoprotein fractions except high density
lipoprotein. High density lipoprotein concentration was
significantly greater in cats fed diets containing an oil
blend, compared with cats fed diets containing corn
oil. Fatty acid synthesis after weight loss was below
the detection limit of the measurement technique.
Conclusions and Clinical Relevance—In cats undergoing
rapid weight loss there is neither increased
triglyceride synthesis nor decreased transport of very
low density lipoproteins from the liver, suggesting that
their involvement in the development of hepatic lipidosis
may be minimal. (Am J Vet Res 2000;61:566–572)