Hello, thanks for using health care magic The brain uses glucose and particularly needs more energy when studying, being stress or when doing any mental activity. The absence of adequate glucose leads to weakness, headache, slow thinking and makes understanding very difficult. Prolonged starvation is not the recommended method of a good diet what ever the goal of diet modification is. Even in case of wanting to loose weight, generally eating should be regular but modified in quantity and quality. Prolonged starvation will lead to peptic ulcer disease which could be severe. However, chocolate is rich in energy but if that s what she wants, she should take it regularly and avoid starving herself for long periods. Hope this helps you. Best regards Dr Achuo