Effects Of Dietary Protein Levels On Abdominal Obesity Syndrome And Body Composition In Rats

It has been hypothesized that restricting carbohydrates with protein intake was found to improve body composition by means of preservation of lean mass, higher satiety and increase thermogenesis. This would eventually improve lipid profile and glucose homeostasis either via a cause-effect of weight and fat loss or protein diet itself. The metabolic syndrome (MetS) or abdominal obesity syndrome generally consists of central/visceral obesity, impaired glucose homeostasis and dyslipidemia, has recently drawn widespread of attention. If the hypothesis of restricting carbohydrate to protein is correct, this intervention would prevent or reverse the development of the MetS. In this study, the rats were fed with varying level of protein for 12 weeks based on the dietary protein levels classification by American Heart Association (AHA), namely CTRL group (n=7, control, 18% dietary protein), HP group (n=7, high protein, 28% dietary protein), VHP group (n=7, very high protein, 35% dietary protein). In general, between the three diet groups, the HP group had demonstrated the significantly lesser body weight and fats [total fat (TotF), abdominal fat (AF), subcutaneous fat (SF) and renal fat (RF)] followed by the VHP group (P < 0.05). The CTRL group, as expected exhibited higher rodent equivalent of the abdominal obesity (P < 0.05) and significantly higher growth in body weight and in fat (TotF, SF, and VF) (P < 0.05). The CTRL group also had poorer blood lipid picture and glucose tolerance that could predisposed them to the development of MetS. Generally, blood lipids, glucose and GTT levels were found to be different across treatment groups, and the disparity becoming more apparent at 12th week compared to week-6. The HP group started to exhibit significantly higher HDL-C (P < 0.05) compare to the CTRL group at the sixth week. At the end of the 12th week, the CTRL group demonstrated notably higher amount of the TotC, LDL-C, TAG/HDL and FGlu compared to the HP and VHP groups (P < 0.05) but significantly lower amount of the HDL-C compared to the VHP group (P < 0.05). The CTRL group also displayed a significantly higher GTT compare to HP group (P < 0.05). After twelve weeks of dietary intervention, the LDL-C in CTRL groups was found to be significantly higher compared to the baseline values (P < 0.05). Conversely VHP groups were found to be significantly reduced (P< 0.05). High protein diet was found to be protective against derangement of blood lipids and blood glucose. Prolonged supplementation of a high protein diet was not shown to cause adverse effects to the bone status, liver and renal functions. Higher enzyme and metabolite values which are within normal ranges are necessary adjustments to adapt to a high protein diet. However, HP group with 28% of dietary protein appeared to be the most attractive macronutrient diet intervention, capable of inducing a favorable outcome against MetS without compromising the liver and renal functions in the rodent model.

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