Dancers shouldn't be following a diet regime that makes them feel deprived. Serious dance students and professional dancers are exercising so many hours a week, they burn up so many calories they should be able to eat fairly normally.
The main thing is not to use sugar to give you artificial energy - so no sugary drinks, no energy drinks, no electrolyte drinks (Gatorade), no lollies. If you need energy before or during class, eat a banana - it will replace electrolytes just as well as Gatorade and is healthier.
If you starve while dancing you'll get injured.