Does iMessage Use AT&T Data

i Have An iPhone 5 From AT&T With A 3GB Plan. Evryone Says iMessage Uses Data & Since The AT&T iPhone 5 Is Built With LTE/4G That Uses More Data I Heard To Make The Data Go Faster ! Everyone I Text Has An iPhone ( iMessage ) & I Rarely Text People With Regular SMS Messages. If The iMessage Does Use Data How Much Data Does It Use Before It Take Some Data Not All Of It Up ?