The advent of the high-tech devices has accompanied by low physical activity but high consumption of westernized style high fat diet leading to high prevalence of obesity worldwide particularly in young reproductive ages of both man and women creating a highly risk factor for fertility disorders.  However, the molecular mechanism underlying the link between overweight and infertility is still unclear. Therefore, the current study planned to uncover the association between weight-gain from high fat diet and the consequent infertility in male rats. The study recruited 30 adult male rats divided equally into two groups: the 1^st group was given normal diet and considered as a control group. The 2^nd group was served high fat diet (HFD) 60% buffaloes' fat for 16 weeks to initiate similar to diet-related obesity. At the end of the 16^th week, blood samples, testicular tissue and semen samples were obtained and underwent biochemical, histopathological, gene expression and microscopical investigation. Compared to control normal diet fed rats, the obtained data showed that there was an increase in blood cholesterol and triglycerides in addition to the unwanted increase in body weight. HFD group showed down regulation of steroidgenic genes StAR and CYP17A with low levels of serum testosterone. Semen analysis taken from HFD males demonstrated low quality represented by low sperm count with reduced viability, motility and increased abnormalities. Testicular tissue sections of positive control group displayed degenerative changes with Caspase3 is crucial for the morphological alterations of cells as well as for the biochemical occurrences connected to the start and end of apoptotic processes and damaged cell indicator NLRP3.In contrast, the same sections displayed marked decrease of inhibitor of apoptosis, survivin. Accordingly, it can be concluded that HFD induced obesity negatively affect male fertility through several mechanisms including general cardiovascular health concern of hyper-lipidemia, hormonal imbalance, low quality semen resulted from degenerative changes of testicular functional tissue.