Leptin is an important factor regulating appetite and energety metabolism; disturbances in its signaling are related to adiposity and contribute to the excessive body fat. About a third of the human population is overweight or suffers from obesity, as well as from associated medical conditions. It is well established that vegetarian, especially vegan, diet is very effective in lowering BMI and body fat, thus, plant-based diets are associated with a lower risk of obesity. The aim of this study was to evaluate the plasma levels of leptin in lacto-ovo-vegetarian and vegan volunteers with normal BMI. The intake of energy and selected diet components such as polyunsaturated fatty acids (PUFA) and carbohydrates was also investigated. The study involved healthy women - 14 omnivores, 17 lacto-ovo-vegetarians, and 11 vegans. All women had a normal BMI (18.5-24.99). The plasma leptin levels were examined with immunoenzymatic test (ELISA). All participants were interviewed to estimate their nutrient intake by performing a 24-hour dietary recall. Both lacto-ovo-vegetarians and vegans had lower plasma leptin concentrations than their meat-consuming counterparts. Every analyzed diet group had a different body fat content, with the highest level in omnivores and the lowest in vegans. All participants had similar calorie, total fat, and total carbohydrates intake. Total PUFA and specifically omega-3 fatty acids consumption was lower in omnivores when compared to both types of plant diet; the same was found for fiber intake. Our results suggest that adopting a plant-based diet may be beneficial for energetic metabolism, as it significantly lowers the body fat storage and circulating leptin levels.