How to stop my spending habit?

I'm trying to save for a phone (the iphone 5) and when i get the money i always crave for a beggars medium size pizza and i buy it and i realize after i buy it that i feel stupid because that moeny was for my phone i went from 130 bucks to zero all because of pizza and junk food… How can i get better at saving money this time i won't spend a dime. (any negative answers will just be reporteed and you lose points… PS i'm not fat i just eat alot lol)

Its hard to save for stuff no matter who you are. I'm trying to save for a nexus but end up spending my money on video games. I say start a budget.