Re: Lunch from both ends?
That's not true.
What IS true, though, that at one time NASA DID play with the idea to feed the astronauts a diet that would not necessitate a bowel movement for the whole trip of 14 days. They went so far as to do experiments (I do not know if any astronauts were involved). The unlucky record holder held out for about 10 days, and, ahem, re-ignition of the digestive tract was not very nice for the test person or the ones to take care of him.
Needless to say, or maybe it is, the test were deemed unsuccessful, and were NOT used on any space flight, much less on one of the moon flights.
You DO know how they handled a number 2 on Apollo, yes? Number 1 was simple – stick it in a tube, pee in a plastic bag, hook the bag up to a valve with connection to the outside, open the valve, observe constellation Urinus, close valve.
Number 2 was a bit trickier. It involved large plastic bags with a funnel opening. It had self-glue adhesive attached. They would glue the bag with these strips to their behind. When they were finished, they dropped some tablet in the whole thing (to prevent fermentation), use the adhesive to close the bag, put the bag in another bag that could be closed easily and securely (just for safety), knead the whole concoction so that the chemicals of the tablet would be nicely distributed, and stored the whole shebang for the whole rest of the trip. Also recall that there was no privacy whatsoever from your fellow crewmates. They had whole pre-packaged kits for that, with the two plastic bags, the tablets, and some wet towels.
Those guys are heroes, goddamnit!