I would rather believe that "3000 calories" was a sarcastic term than literal. On a strenuous day of survival and filming for the show, Les could easily expend twice that many calories over say 15 or 16 hours of work, carrying 50 pounds of gear back and forth, going up and down hills, bush whacking, shivering, not sleeping properly, stress, adrenaline and working around a camp area.

There is a big difference also between a loss of calories and the loss of body weight. 3500 calories may equal a pound but if the body loses a pound it may not be 3500 calories. It could be water.

I have done Ironmans where my heart rate monitor showed I burned 12,000 calories or a bit over 3 lbs. during a 14 hour race but on the scale I lost 23 pounds. Yes 23 pounds. Water a significant part of that and almost all the wieght put back on by the the next weekend or so.