The purpose of this review is to explore the relationship between weight loss (WL), specifically reductions in body mass index (BMI), and increases in testosterone levels. Obesity and excess body fat are linked to reduced testosterone levels, which can lead to metabolic dysfunctions, reduced libido, and diminished muscle mass. To attain this purpose, this review will summarize current evidence on how weight reduction interventions, including dietary changes, exercise, and bariatric surgery, affect testosterone production in overweight and obese individuals. WL, particularly through fat reduction, has a positive influence on testosterone levels. Both moderate and significant reductions in BMI are associated with notable increases in serum testosterone levels. Dietary interventions, particularly low-carbohydrate and Mediterranean diets, have been linked to increased testosterone production in men with obesity. Exercise, particularly resistance training, has also been shown to improve hormonal profiles by lowering fat mass and boosting testosterone levels. Additionally, bariatric surgery has been identified as one of the most effective methods for increasing testosterone in morbidly obese individuals, with improvements sustained over time. The findings have indicated that there is strong evidence that WL, particularly through reductions in BMI, leads to increased testosterone levels. This relationship is mediated by improvements in insulin sensitivity, reduced inflammation, and lower levels of aromatase activity (the enzyme that converts testosterone to estrogen in fat tissue). Effective interventions, including diet, exercise, and bariatric surgery, have the potential to restore hormonal balance, improving overall health outcomes for men with obesity or higher BMI. Further research is needed to optimize interventions and explore long-term benefits.