You are right. Eating that late at night will contribute to weight gain. Though your daughter is on her feet and doing a lot of walking during her shift as a waitress, all that exercise is before she is eating. Now, if she ate during her dinner break, let's say middle of her shift, she would still have several hours to burn off the consumed calories. But, by eating late and salty, high calories foods then going to bed, she is not burning those consumed calories. The bad chest pain which she had last night is most likely acid reflux. If she can change her eating habits, she may find that she can manage her weight and symptoms of acid reflux.