How can i enjoy my self this ounce without gaining wieght?

you see with crash dieting

and eating healthy and exercises

ive lost tons of wight and changed my look completely

(about 50 lbs)

well my mothers B-day is coming up and she wants to go to Ginos east

chicago style deep dish pizza!

i don't want to not go it will break her heart

so i want to just maybe enjoy my self this ounce,but how?

can i like make a small smoothie in the Morning

spinach

strawberries

blue berries

raspberries

pine apple

ice

the only have Gino's east the hole day

and go for a jog the next morning??

will that work

any other ways??How can i enjoy my self this ounce without gaining wieght?
you still have to be able to live....the only way to have a healthy diet is to allow yourself have treats every now and then...how about only eating one slice and have a light salad as your meal?