Plasma LCAT Activity and Lipid Subfraction Composition in Obese Beagles Undergoing Weight Loss

The relationship between lecithin:cholesterol acyltransferase (LCAT) activity and weight loss in dogs was investigated. Four experimental weight-loss diets were fed to 12 obese female beagles for 56 days in a partial crossover design (n = 6). High- (HGI) or low- (LGI) glycemic index starch and diacylglycerol or triacylglycerol oils were combined to compose experimental diets with similar fatty acid profiles. Food intake and body weights were measured daily and weekly, respectively. Fasted blood samples were drawn at day 0, day 28, and day 56 to measure plasma LCAT activity and total (TC), unesterified (UC), and esterified (EC) cholesterol concentrations, and for fatty acid analysis of the phospholipid (PL) and EC fractions. The LGI groups lost more weight than the HGI groups due to starch digestibility differences. An HGI starch effect on TC and UC concentrations was observed but was unrelated to weight loss. LCAT activities increased over time but were not different after controlling for percentage weight loss. However, a positive linear correlation was found between LCAT and UC concentrations in all groups. Plasma PL fatty acid profiles reflected the diets fed, but increases in 16 and 18 carbon saturated and monounsaturated fatty acids in all groups appeared to be an effect of fatty acid mobilization from storage sites. Both plasma PL and EC fatty acid profiles were similar with both acylglycerol types and EC fatty acids reflected linoleic acid specificity with minimal diet or time effects.