Now, here's my opinion, and I know it might be wrong. Anyone, please feel free to correct me, but: Everything I've read suggests that 1lb muscle requires about 50 calories a day to maintain. The workout programs these contestants are using are focused solely on cardio, or very heavily focused on cardio. If as part of the 239lb weight loss, Mr Cahill lost 8lbs-10lbs of muscle (and never regained it), there's your enti…
They mentioned that they have a lower metabolic rate than someone of the same size. I doubt they have less muscle than the average person at their weight
With as much cardio as they did, with as little as they ate, I can easily see them having a different body composition than someone else of their height/weight.