Young leaflets of Cycas circinalis L. (Cycadaceae) are used as a delicacy and a medicine in Sri Lanka, Philippines, Indonesia and Malaysia. However, only few pharmacological or chemical studies have been done to evaluate the reported medicinal importance of the species. In the present study, albino Wistar rats were tested against the young leaflets of C. circinalis to determine the changes in the activities of specific liver enzymes such as Alanine amino transferase (ALT), Aspartate amino transferase (AST), Alkaline phosphatase (ALP), Gamma glutamyl transferase (GGT) and creatinine. The fatty acid constituents present were analyzed using gas chromatography–mass spectrometry (GC-MS). When the albino Wistar rats were fed daily with 1.0 g of young leaflets of C. circinalis over a period of four weeks, the body weight increment was significantly higher in test group than the control. Slight elevation of ALP and GGT levels were observed, however, the difference was non-significant. The AST concentration was found to be significantly lower (p<0.05) in test group than the control (55.1±3.7 U/L). The ALT activity in rats fed with C. circinalis leaflets was slightly lower than those of the control. However, the difference was not statistically significant. The n-Hexadecanoic acid (palmitic acid) was found to be one of the most abundent fatty acids present in young C. circinalis leaves. Palmitic acid has been shown to alter aspects of the central nervous system responsible for the secretion of insulin and to suppress the body's natural appetite-suppressing signals from leptin and insulin - the key hormones involved in weight regulation. It could be suggested that the weight gain by albino Wistar rats fed with young C. circinalis leaves may be due to the presence of high level of palmitic acid or their derivatives in the leaves.