Obesity results from a prolonged imbalance between energy intake and energy expenditure, as depending on basal metabolic rate, heat production, thermogenic effects of the diet and physical activity. Diet-induced obesity (DIO) in rodents can be achieved by different regimens and approaches. Diets providing a high fat intake have been established as a “gold standard” to generate obese rodent models and have proven to initiate pathologies similar to those encountered in humans. However, this dietary treatment is far from being standardized and its relevance has been criticized on the basis of findings in humans that total energy intake rather than fat per se determines body fat accumulation in humans. Hence, varieties of high fat diet regimens have been introduced by providing a choice of several palatable food items of variable composition, appearance and texture in addition to a non-purified diet. Further male rats have been considered in developing all types of obesity models and no rationale has been provided as of this discrimination and negligence of using female rats. Another pitfall in the obesity model development is that of the choice of the strain of the rats used for the study. The basis on which the specific strain is being chosen still remains controversial. This present study aimed at comparing and validating different diet induced obesity models utilizing different high fat diet regimens in different strains and gender. Sprague-Dawley and Wistar male and female rats were offered different high fat diet regimens for 7 weeks to induce obesity. Marketed high fat diet group served as a standard. Evaluation parameters like food intake, calorie intake, water intake, % increase in body weight, plasma total cholesterol, HDL-C, LDL-C, VLDL-C, triglyceride, oral glucose tolerance test and insulin tolerance test were performed to assess the efficacy. Diet specific, strain specific and gender specific variation was observed in case of diet induced obesity models. Marketed diet produced better lipid profile and also produced signs of diabetes and thus can be used for obesity-diabetes studies. Vegetable ghee::coconut oil diet produced higher increase in lipid profile in shorter span of dietary manipulation of 4 week and also gave confirmation of equal amount of fat ingested by the entire group. In-house prepared HFD produced better results at the end of 7 week of dietary manipulation. Strain wise Sprague-Dawley rats produced better results and gender wise males showed greater increase in lipid profile than that of females. The results of the study provide clear evidence that vegetable ghee::coconut oil (3:2) diet serves as a better model of hyperlipidemia/obesity as it requires shorter time of dietary manipulation and economically also is more feasible. Marketed diet produced better results but takes longer time to develop and also causes glucose intolerance and insulin resistance thus can serve as a model of obesity and diabetes. Strain wise and gender wise Sprague-Dawley rats and males respectively served as a better model for obesity. The reason for this can be attributed to the metabolic activity as concluded from the calorie intake values that persists in Sprague-Dawley rats and that in males. Further study is required to derive proper conclusions.
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