Rod trust me. Back in the day i was a amateur competition bodybuilder... Weighed 230lb and had 8% body fat 24 hours before comps...Fat loss cant occur without some degree of muscle reduction as the two are interchangeable but there are ways of minimizing muscle loss during this period, unless u have insane genetics as pointed out by another poster. You want a minimum 20mins on bike at 90% capacity (after 20mins body will start to burn fat and not draw on minerals from muscle) and maximum of 30 mins...
Also try overhead and side rope ab pulldowns with weights, keeping form 100% of the time, otherwise u wont isolate the targeted area(s) intensely enough to add meaningful size to your abs and obliques in the longterm....Additionally go to failure during sets and have a friend spot you for 5 extra reps or so (taking only enough weight so that ur still in control of the weight)...No pain no gain in this game Rodney...GL man