Background: Healthy eating is one of the main factors of maintaining health. Certain diets such as flexitarian, vegetarian and vegan can be associated with a healthy lifestyle. These diets have recently become more common. Aim: This review aims to summarize the characteristics of a flexitarian, vegetarian, and vegan diet by comparing these specific nutritional trends through the processed literature. Methods: Electronic searches were performed on the Google Scholar database, Medline, PubMed, and Science Direct. The manuscript summarizes publications on flexitarian, vegetarian, and vegan diets. Furthermore, it examines the relationships between different nutritional trends as well. Result: The summarized vegan (100% plant-based diet), vegetarian (plant-rich diet), and flexitarian (plant-based with high-quality meat consumption diet) have become the focus of results through this literature. Conclusion: Flexitarian, vegetarian and vegan diets contribute to a healthy lifestyle and sustainable agriculture by following nutritional recommendations. The common basis of diets is to appreciate natural values and maintain health.