A couple of years ago I saw a BBC Horizon television documentary about sugar and fat. One section mentioned three experiments performed by Dr Paul Kenny in which rats were given their ordinary rat food plus and unlimited supply of:
Experiment A. Unlimited sugar
Experiment B. Unlimited fat
Experiment C. Unlimited sugar and fat mixed together (50:50)
The stated results were that in experiment A the rats did not put on any weight, in experiment B the rats put on weight but not much and in experiment C they put on loads of weight and would eat the 50:50 mixture to the exclusion of their ordinary food. I also remember the documentary said the 50:50 ratio was critical and if the ratio was shifted too far in either direction then the weight gain effect reduced sharply. It was postulated that the reason for the satiety error was that sugar and fat don't often occur together in nature so the rats (and maybe people too) haven't evolved the biochemical feedback mechanisms for determining when they are satiated from such a mixture.
Edit: (Dr Kenny's work seems to be related to this earlier paper)
My question is this: have there been any follow-up experiments from this work? Either with humans, or perhaps with other unnatural mixtures like sugar/salt? or a triple-mix of sugar/fat/salt.