Most people use traditional exercises to exercise their abs. While this is great that they are putting forth the effort, isolating your rectus abdominus muscles will not get you the waist slimming ab results you want.

In order to actually slim your waist and get rid of your muffin top or beer belly, you instead have to coordinate the use of your inner core muscles. More specifically the transverse abdominus and internal obliques (although all uscles are used to some degree).