Never listen to anything I say! It was a study by the Swedish army, not the Norwegian one.
Documentation, in Swedish, can be downloaded from BushcraftUK!
The Handbok Överlevnad.
http://www.bushcraftuk.com/downloads/pdf/h_overlevnad.pdf
The relevant sections begin on page 41, with the A/B comparison of starvation vs 500 kcal a day beginning on page 51.
Cut and paste the text into
Google translate to translate the text into English.
Thanks to Paul at
Frontier Bushcraft for reminding me where the original article had come from.
Of course, I must now point out that the data behind those statements are at least 30 years old by now, that the studies done by Källman, that these conclusions were mostly based on, were flawed (i.e. we don't really know what the correct conclusion should be, due mainly to crappy analysis methods and often quite small groups). Lars Ståhle and Elisabet Granström has done some resent studies that appear to validate the hypothesis that starvation in itself is not as bad as we have thought it was. Vitamin (and mineral?) deficiency may turn out to be a more important issue (e.g. B1 is essential for the krebs cycle) for long and medium term, and sleep deprivation for the shorter term.
I (and others) have been out for 10 days with quite low caloric intakes, and while one has been "low and slow", all members of the group have been functional, and after a proper meal we were pretty much back to normal (note: lost muscle mass that negatively affected athletic performance for some time was reported by at least one participant). My own suspicion is that if the body is in ketosis mode one will function fairly well, but that that takes a while to get there and that occational bursts of carbohydrades shuts down the ketosis.
It is a topic of debate, where no one can in honesty say that they have the final answer. More studies, well designed studies, are needed before we have the final answer. One study that I would like to see is what happens to people on ketosis diets (LCHF, Atkins, etc) if subjected to starvation. I suspect that blood glucose will be much more stable for those subjects.