A short break from studying

If you have a lot of study, you have to make small breaks and eat snacks with high nutritional value and  energy.I used to eat some fresh fruits or a small piece of chocolate. On the one hand fresh fruits make you look healthy because they have vitamins energy and vitality, but from the other a  small piece of chocolate can't destroy the balance of your diet, gives you energy and it's something that almost everyone  likes. So what  should i choose ?