I've been on a NOLS course in the late seventies. We went four days without food backpacking across 45 miles of rugged Wyoming terrain - by design to teach us. Food is the least of concerns in short-term survival situations.
Did a semester of NOLS in the early nineties. Your post is indeed true. Lived off bouillon for the last two days of one of our journeys (not by choice but youthful foolish indulgence of rations for the first three days). Cheers