BACKGROUND: The typical Korean diet includes rice, which is usually served in a rice bowl. We investigated the effects of a meal plan using rice bowls of varying sizes on dietary energy intake (EI), body weight (BW), and blood glucose levels. METHODS: Forty-two obese women with type 2 diabetes mellitus were randomly assigned to use either a 200 mL small rice bowl (SB), a 380 mL regular rice bowl (RB), or to a control group (C). Both intervention groups were asked to reduce their EI by 500 kcal/day for 12 weeks and simple instructions for using the assigned bowl were provided. Dietary EI and proportion of macronutrients (PMN) were estimated from 3-day dietary records. RESULTS: Reduction of EI was more prominent in the SB group compared to the RB and C group, although EI decreased significantly from baseline in all groups. Carbohydrate and fat intakes of the SB group were decreased greater than those of the RB and C group. However, changes in PMN were not significant across the 3 groups. Reduction of BW and HbA1c levels in the SB group was more prominent compared to the C group. Although, BW and HbA1c were decreased significantly from baseline in both bowl groups. There was no statistical difference between the two groups. CONCLUSION: The small rice bowl-based meal plan was effective at reducing EI, BW, and blood glucose levels, and the observed reductions in EI, carbohydrate, and fat intake were greater than those of the regular rice bowl-based meal plan.