The treatment of obesity and cardiovascular diseases is one of the most difficult and important challenges nowadays. Weight loss is frequently offered and aimed at improving some of the components of the metabolic syndrome. Among various diets, carbohydrate restriction is popular, specifically ketogenic diets, which are very low in carbohydrates and usually high in fats and /or proteins. Results are controversial, but some benefits such as weight loss and improved glycemic control have been described. Nevertheless, these effects seem to be limited in time. Moreover, these diets are not totally safe and can be associated with some adverse events such as the development of nonalcoholic fatty liver disease. The aim of this review is to discuss the role of ketogenic diets on different cardiovascular risk factors based on available evidence.