Effect of dietary protein quality and fatty acid composition on plasma lipoprotein concentrations and hepatic triglyceride fatty acid synthesis in obese cats undergoing rapid weight loss

Objective-To determine effects of dietary lipid and protein on plasma lipop rotein 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 i deal body weight and then randomly assigned to receive 1 of 4 weight reduct ion diets (6 cats/diet) at 25% of maintenance energy requirements. Diets co ntained a low or high quality protein source and a lipid source deficient o r 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 l ipoprotein concentrations. Synthesis of these substances was measured by us e of isotope enrichment. Results-Plasma total cholesterol concentration and concentration of lipopro tein fractions increased after weight gain, compared with baseline values. Weight loss resulted in a significant decrease in concentrations of all lip oprotein fractions except high density lipoprotein. High density lipoprotei n concentration was significantly greater in cats fed diets containing an o il blend, compared with cats fed diets containing corn oil. Fatty acid synt hesis after weight loss was below the detection limit of the measurement te chnique. Conclusions and Clinical Relevance-In cats undergoing rapid weight loss the re is neither increased triglyceride synthesis nor decreased transport of v ery low density lipoproteins from the liver, suggesting that their involvem ent in the development of hepatic lipidosis may be minimal.