I maintain a size 0 with a vegan diet.  I took many steps in my road to Veganism, starting with this web site.   http://www.greattastenopain.com/cmdt.asp?id=849605 it is a great way to get started, and I eat brown rice pasta, vegan bread (frozen health food section of most grocery stores) brown rice instead of white and very little boxed or processed food.  Sugar is tricky though labeled in many different forms organic style is best, I substitute Agave necter for sugar twice as sweet and use much less also less calories. good luck it is tough must have lots of will power,  sugar once or twice a month is ok