They used to have a provision for this where you'd pay an 'entertainment fee' and not dine. Now the rule is that if you're an adult sitting there, you pay the full adult price.
However, the good news is that at a buffet they have a very wide variety of itmes, and something there is sure to fit the bill for you. Some buffets have even been known to make a special item plain for you. (If you can't have sauce on your chicken, they'll make a plain breast for you)
There's also a wide array of fruits, veggies and good healthy/fresh items.