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Access Type

WSU Access

Date of Award

January 2011

Degree Type

Thesis

Degree Name

M.S.

Department

Nutrition and Food Science

First Advisor

Pramod Khosla

Abstract

Dietary fat has been a matter of debate for the raising rate of obesity in the last decades which lead to low-fat and reduce energy recommendation. However, emerging evidences suggest that macronutrient composition role in weight reduction is inconclusive. Therefore, the objective of this study is to determine the effects of fatty acids modulation on weight changes, lipid profiles and adipose gene expression following weight gain and weight loss state. Golden Syrian hamsters (n=90) were randomly assigned to one of the six diet groups that comprise of lauric-myristic acid based diets(60%LM, 45%LM, 30%LM), palmitic acid based diets (45%PA, 30%PA) or a low fat based diet (21%control) with varying percent of energy from fat. Following 7 weeks of ad libitum diets, 48 hamsters were sacrificed while the remaining 42 were reassigned into 4 diet groups (60%LM, 45%PA, 30%PA and 21%control), and were fed calorie-restricted diets for 7 weeks with 40% less in total calories as compared to ad libitum phase. Weight changes were recorded, fasting plasma lipid profiles (TC, HDL-C, non-HDLC and TG) were measured and adipose mRNA were obtained and measured for expression levels of 5 lipogenic and lipolytic genes (SREBP-1c, LPL, FAS, PPARɣ, and HSL). Results showed that magnitute of weight changes dependent on the amount of calories consumed and calories restriction result in similar weight loss regardless of the diet groups. Lauric-myristic rich diets at 60 and 45% of fat from total calories results in elevation in TC, non-HDL and TAG following ad libitum diets, but were not significantly difference when TC/HDLC ratio is taken into consideration. Calorie restriction result in significant improvement in lipid profiles in all diet groups. PPARɣ were down-regulated following ad libitum feeding in diet groups containing >45% fat but were up-regulated in others. Adipogenic genes (LPL, FAS) were down-regulated as compared to 21% control in a pattern consistent with energy consumption and weight changes. Different pattern of gene expression levels suggest that there were different metabolic activities exist at different energy levels from fat, saturated fatty acid compositions and during weight gain and weight loss phases.