You always have to train your muscles to be able to say "I have them" but I guess there isn't a right answer.
I know cases of guys who were doing a military course and they lost 17 pounds in the first week, they got stupid ripped in the mid section and they were eating ridiculous amounts of pizza, chocolates and hamburguers the whole week, all day long, yes, all day long, so in this case the kitchen was a mess out of any logic.
This ridiculous way of eating was overwhelmed by the ridiculous way of doing cardio and exercises of all kinds.
On the other hand we have for instance the ketogenic diet which has been documented to be the fastest way of losing fat drug free.
I would say "Abdominals are made on a super healthy equilibrium"