Leptin is derived from the Greek word leptose, which means thinness, and was discovered in 1994 by isolating the obesity gene. This substance is a protein hormone with a helical structure similar to cytokines, which is mainly synthesized and released by the subcutaneous fat cells in a constant pulsating manner with a peak secretion near midnight. A key factor in controlling energy and metabolism, which has an impact on body weight, is leptin. Leptin, which is produced by the obesity gene, has been the subject of extensive investigation in recent times. Researchers have reported contradictory findings about the effect of physical activity in different situations on the regulation of leptin secretion from adipose tissue sources. This review article is focused on conflicting studies and the effect of different intensities of physical activity on leptin and leptin's response to intense activity and training periods. This study reviews research that has examined the effect of various types of exercise on leptin in the form of a literature review. Recent reports on the effect of physical activity and exercise on leptin concentrations are conflicting. Some researchers have determined that exercise can reduce leptin concentration, depending on the duration of physical activity and calories consumed. While some researchers have not reported any change in leptin concentration. The present review indicates that physical activity longer than 60 minutes with substantial energy expenditure (>800 kcal) of exercise is required to observe reductions in plasma leptin concentrations in non-athletes.