you have never seen riders go from riding GC at GT level, then ride a pursuit at ~78, then ride a GT at~70. Mcgee did it at about ~72, and one kg heavier at Athens. Brown and Ogrady were about 1kg heavier on the boards, then Stuey flicked over onto the road for the 240km rr.
These are elite athletes, professionals, they cannot decide on whim to change their body shape and lose non-fuctional body mass, overnight, because they are already training at 100% at a caloric equilibrium. The only way to lost such weight would be to starve yourself, but they need to be pro athletes, with significant nutrition intake.
The only reason these new era riders like Horner and even Nibali, and Hesjedal, and Froome, and Wiggins, turn up with such profound weightloss is because of new peptides like lipotropin.
http://en.wikipedia.org/wiki/Lipotropin. p'raps, some AICAR, but I would be leaning to lipotropin. Robert Bartko and Jens Lehmann rode in the wrong era, a little AICAR and lipotropin and they would have won the TdF too <eyesroll>