Where did you get the information that it is unhealthy for a 230 pound person to eat 1200 calories a day? I understand that sodium,potasium,etc.. are necessary

Where did you get the information that it is unhealthy for a 230 pound person to eat 1200 calories a day? I understand that sodium,potasium,etc.. are necessary, I'm just asking about why you think that the calories are a problem when 230 pounds?