Greetings first check with your daughter the weight she has gain after joining in new place. Is it really the eating habit changes or other factors also involved. Fast food is not at all healthy as it lacks in fiber, vitamin and minerals and loaded with fats and carbs. Counsel her about the adverse affects of these kinds of food and teach her to include healthy options like baked and roasted snacks, roasted chana, murmura, steamed foods like idly dhokla, sprouts
which she can use at hostel also. She can also include fresh fruits ,vegetables, nuts like almonds
walnut in diet to avoid munching of fast foods. She can include these foods in between the meals so that she feels fulfil. All the best.