The present pilot study examined the acute effect of a low-carbohydrate diet (LCD) for lunch and dinner on glycemic parameters in healthy young Japanese women. Sixteen women wore a flash glucose monitoring system for seven days and consumed test meals on days four to six. Participants consumed a standard-carbohydrate diet (SCD) during the study period, except for lunch and dinner on the day of the LCD. The energy ratios of carbohydrate, fat, and protein in the SCD were 64 %, 21 %, and 15 %, respectively, whereas those in the LCD were 30 %, 49 %, and 21 %, respectively. The mean blood glucose, mean amplitude of the glycemic excursion, incremental glucose peak, and incremental area under the glucose curve (IAUC) of lunch and dinner in the LCD period were significantly lower than those in the SCD period. However, the next day, the postprandial blood glucose concentrations and IAUC of the SCD were significantly higher than before consuming the LCD, although the SCD meals were identical throughout the study period. This indicates that switching from an LCD to an SCD causes an elevation in the blood glucose parameters on subsequent consumption of an SCD in young Japanese women. This result suggests that this diet may cause hyperglycemia in people with type 2 diabetes.