Recently, patients with metabolic syndrome such as obesity, diabetes, hypertension and hyperlipidemia have been increasing worldwide and nutritional therapy is indispensable. There has been discussion and controversy about Calorie Restriction (CR) and Low Carbohydrate Diet (LCD) for years. Originally, LCD was started by Atkins and Bernstein [1-3], and author and colleagues have started and developed LCD in Japan by books, seminars and workshops through Japan Low Carbohydrate Diet Promotion Association. Three kinds of LCD meal were simple and useful for understanding and developing of LCD, which are super, standard and petit LCD [4]. We have also continued clinical researches concerning ketone bodies, Morbus (M) value, comparison of CR and LCD and insulinogenic index (IGI) for CR breakfast including 70g of carbohydrate [5,6]. Among our reports, representative data of CR and LCD would be as follows [7]: patients with type 2 diabetes mellitus (T2DM) were divided into 3 groups (low, middle, high) by HbA1c value with 6.1%, 7.9%, 9.3%, respectively. Meals were provided CR on day 1,2, and LCD on day 3-12. Comparison of the value on day 2-day 12 in each 3 group revealed that fasting glucose was 164-125 mg/dL, respectively. M value means the average glucose and mean amplitude of glycemic excursions (MAGE) in a day [8]. These results suggested the clinical efficacy of LCD for glucose variability and lipid metabolism in short period with only in 10 days.