What can I do with my date? without making him pay?

I've seen him 3 times since he's come back from school and EVERY TIME we go out, he takes me to a restaurant and pays for my food. I am now on the atkins diet (can only eat meat and cheese) so I want to go to a sushi buffet and eat sashimi but will he thik that's weird if we are eating EVERY TIME we go out? Last time I wanted to eat sushi and he said that it's too expensive. (He eats sushi with his brother all the time) but I guess since he was paying for the both of us, he wanted something cheaper.