Body composition analysis (BCA) became an important tool in health care to predict and study obesity. This study aimed to compare two methods of BCA: Lee Index (LI) and Time Domain - Nuclear Magnetic Resonance (TD-NMR). The study entailed administering a high-fat diet to a cohort of 8 mice over a span of 16 weeks, juxtaposed with maintaining a separate group of 10 mice on a standard diet. Throughout the diet, both groups underwent TD-NMR analysis at the end of the 16 weeks. The LI was calculated at the end of the \(16^{\text {th}}\) week. TD-NMR revealed an increase in fat mass in the high-fat diet group, while the LI did not show consistent patterns for either group. In this study, we present the two methods of BCA – the LI and TD-NMR – along with a description of the animal experiment. At the conclusion of the experiment, it became evident that LI was not capable of providing reliable analysis or accurately predicting obesity. Furthermore, none of the LI results correlated with the results obtained from TD-NMR.