Any net imbalance between the amount you eat, and the amount you excrete whilst on the planet is surgically removed from your body weight when you leave.

— The Hitchhiker’S Guide To The Galaxy Book (Peter Jones)

14 seconds sound clip from The Hitchhiker's Guide to the Galaxy (1981) - Episode 2 sitcom.

You can hear this line at 00:12:46.858 in the Blu-ray version of the TV Series.

Quote context

[...]

(Spaceship)

- The Hitchhiker's Guide to the Galaxy is a wholly remarkable book. The introduction starts like this: Space, it says, is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is.

- I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space. Listen... And so on.

- After a while, the style settles down a bit and it starts telling you things you actually need to know.

- Like the fact that the fabulously beautiful planet Bethselamin is now so worried about the cumulative erosion caused by over 10 billion visiting tourists a year...

- Any net imbalance between the amount you eat, and the amount you excrete whilst on the planet is surgically removed from your body weight when you leave.

- So, every time you go to the lavatory there, it is vitally important to get a receipt.

- In the entry about dying of asphyxiation, 30 seconds after being thrown out of a spaceship, it says that what with space being the size it is, the chances of being picked up by another craft within those seconds are 2 to the power of 260199:1 against.

- Which, by a staggering coincidence, was also the telephone number of an Islington flat, where Arthur once went to a very good party.

- Where he ate some very good food, had some very good drinks, with some very good friends, and met a very nice girl whom he totally failed to get off with.

[...]