Despite the growing interest in low carbohydrate diet (LCD), a methodology for nutritional counseling to ensure their effectiveness and safety has not yet been fully established. This narrative review summarizes the main points of research on LCD, outlines the merits and demerits of this diet, and proposed practical application methods for nutrition counseling. The amount of carbohydrates in the diet used in studies of LCD varies widely, and a variety of diet are used as comparisons. In addition, subject dropout and poor adherence to the diet can make evaluation of the diet difficult. The effects of LCD on weight loss and diabetes management are not different in the long term compared to other diets such as low-fat diet. LCD tend to be high in fat, protein, and salt, which raises concerns about the risk of atherosclerotic disease. In order to take advantage of the benefits of LCD, it is essential to provide careful guidance on carbohydrate intake, substituting plant proteins and polyunsaturated fatty acids for carbohydrates, and reducing salt.