Purdue University researchers revealed earlier this month that the artificial sweetener saccharin caused rats to put on more weight than others fed sugar. Manufacturers of the sugar substitute responded that this study oversimplified cause for obesity, which involve many factors. See this report by Los Angeles Times Staff Writer Denise Gellene for both sides of the story.
I have no idea if this result will extrapolate to humans, but I would not be shocked if it did. As I gain life experience (that is, get older), my skepticism about generally-held, but never tested, assumptions grow stronger. I find myself more and more reluctant to jump on board with what most people come to accept as irrefutable. Thus a counterintuitive result like this, that something thought to reduce weight actual induces it, does not surprise me.
If you find this result to be difficult to swallow (ha ha), think of how hard it must have been to give up the obvious fact of the earth being flat. Famed physicist Stephen Hawking opens his classic book A Brief History of Time with the story (probably apocryphal) of a flat-earth believer who says to a cosmologist that the earth is supported on the back of a tortoise. When asked how this can be supported, she triumphantly declares that it is turtles all the way down.
“The path of sound credence is through the thick forest of skepticism.”
– George Jean Nathan