The effect of different dietary fatty acids upon the development of obesity and insulin resistence

Donnellan, Christopher Edward (1999) The effect of different dietary fatty acids upon the development of obesity and insulin resistence. University of Southampton, Doctoral Thesis.

Abstract

This study aims to compare the effects of feeding high fat diets containing different fatty acid composition upon adipose tissue metabolism and whole body lipid handling. Male C57B16 mice were fed for seven weeks on either a low fat (2.5% fat by weight) control diet or on one of four high fat (20% fat by weight) diets containing either coconut oil (CO), olive oil (OO), safflower oil (SO), or fish oil (FO) as the principle fat source.

Mice fed on the OO and SO diets gained significantly more weight than mice fed on the other diets, had larger epididymal fat pads and a greater amount of total body fat. Mice fed on the high fat diets consumed the same amount of food, which was significantly less than the amount eaten by LF-fed mice. However, due to the higher energy density of the high fat diets, mice fed these diets consumed more energy than the LF-fed mice. By measuring energy intake and total carcass energy, it was calculated that FO-fed mice had higher energy expenditure than mice fed the other diets.

To understand why some high fat diets promote obesity, while others do not, various tissues and blood samples were taken from the mice and analysed. FO-fed mice had lower plasma traicylglycerol and non-esterified fatty acid concentrations compared to the other high fat-fed mice. Plasma leptin levels were positively correlated with body weight, such that the more obese mice (OO- and SO-fed) had high leptin levels, while leaner mice (LF- and FO-fed) had lower leptin levels.

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