Sounds like he got the eating and sex part mixed up with eating and swimming. (I'll bet that's his advice to anyone, anytime about sex. Downright anal, if you ask me.)Do not have sex right after eating. You should allow two to three hours to digest your food. Be sure you are well rested." (p. 7)
Wouldn't work for me anyway. Two hours after dinner, my wife's asleep!
Best wishes,