Purpose To gain a better and more comprehensive understanding, this study aims to investigate the literature to explore the two popular diets’ health benefits and concerns. Google Scholar and PubMed were used to search for available and relevant nutrition and health articles that pertain to the benefits and concerns of plantogenic and ketogenic diets. Search terms like low carbohydrate, diet, ketogenic, vegetarian and chronic diseases were used. Information was obtained from review articles and original research articles and checked for accuracy. Ketogenic diets have been used for a long time for convulsion in children and now reappeared for weight loss purposes. Design/methodology/approach Ketogenic and plantogenic (plant-based) diets have been adopted today by many professionals and the public. Findings Ketogenic diets have been used for a long time for convulsion in children and now reappeared for weight loss purposes. Plantogenic diets also have been practiced for many years for religious, health and environmental reasons. Compared to plantogenic diets, ketogenic diets lack long-term evidence of its potential benefits and harm. Research limitations/implications Maybe Lacto-ovo vegetarian and pesco-vegetarian (eat fish but not meats) diets are OK. However, for strict plantogenic diets (total plantogenic/vegan diet), the risk of mineral or vitamin deficiency is present (Melina et al., 2016). Of particular concern is dietary vitamin B12, which is obtained mostly from animal sources (Melina et al., 2016). A long-term deficiency of vitamin B12 can lead to macrocytic anemia and cause neuro and psychological effects (Obeid et al., 2019). Also, omega-3 fatty acids may be deficient in such a diet and probably need to be supplemented on those who follow the total plantogenic diet (Melina et al., 2016). Other deficiencies of concern would be zinc, iron, calcium, vitamin D and iodine (Melina et al., 2016). Another disadvantage is that many junk foods could be easily classified within the plantogenic diet, such as sugar, cakes, French fries, white bread and rice, sugar-sweetened beverages and sweets in general. These items are related to higher weight gain and, consequently, to a higher incidence of diabetes and other chronic diseases (Schulze et al., 2004; Malik et al., 2006; Fung et al., 2009). Originality/value Plantogenic diets were concluded to have sustainable health benefits for humans and the environment over ketogenic diets, which could be used but under professional follow-up only.