Jennifer - The Alli literature that comes with the starter package shows the South Beach Diet on the high end of fats that's permissible on Alli. If someone uses South Beach, they've got to be extra careful that their intake stays balanced between fats and carbs. Most of the Alli dieters state that if they eat toward the high end of the fats allowed on Alli, they're more successful. One just must be careful not to exceed the recommended fats on Alli (which South Beach is rather liberal about), otherwise the dieter would have treatment effects. Hope this helps. - Jane