Is it normal to feel weak when on diet? i am eating 1 cup rice, vegetables, & fruits. i have a fatty liver that is why i am doing. taking ursential.

Yes and that's not: normal. a diet that is full of the right nutrients, in the right proportions to you individually is good for optimum nutrition and for a successful long term diet. I would suggest enlisting the help of a dietitian to make sure you are get your daily recommend allowance of nutrition.

Well : Calorie restricted severe diet can cause weakness if it's extremely low calories. Consult your physician for specific advice