"Abs are made in the kitchen" - this is a motto ingrained into me back in my competitive bodybuilding days of the 1990's.
A multitude of infomercials, supplement suppliers and well-paid spokespeople try to promote a quick-fix six-pack solution, although there is no such thing as a cutting diet, abs diet, mass-gaining diet, etc.
Bottom line is the "Law of Thermodynamics" -- weight reduction can only take place when there is more energy burned than consumed.
Likewise, weight gain (muscle gain) can only take place when more calories are consumed than burned.
'Abs made in the kitchen' reflects the fact that you CAN diet off a bad workout, but you CANNOT workout a bad diet.