When you eat rice, your body digests the rice to simple sugars that go into the blood. This is glucose. In order to control the glucose level in the blood, the body produces a hormone, insulin, whose job it is to take up the glucose and store it in the muscles. After eating rice, there is an increase in insulin levels and this tends to makes us sleepy and also moody at times. Try to include food that has protein in it to help control the insulin production. (try eat meat, nuts with the rice). I also need to ask the following questions - how old are you? - is your weight correct? 31kg? - is it correct that you eat soil , or is that meant to read oil ? I will then continue answering your questions. Hope this helps!