This is interesting. Are there any theories or studies on why this might be the case?
Yes; the theory goes something like this.
1) You drink artificial sweetener.
2) Your tongue registers 'sweet'.
3) Your body produces insulin.
4) ...but there's no sugar to digest. Darn!
5) Your blood sugar is dropping! You should probably eat something.
Rinse and repeat.
If I'm right about the general mechanism, this is probably the case with multiple artificial sweeteners, not just aspartame, which also has the distinction of being
defined as a neurotoxin. It
also screws with your intestinal flora, in case anyone needed more incentive to stay away. One study suggests that
this might be how it shifts people towards glucose intolerance.
My theory requires that anything that fits into a sweet receptor can trigger insulin response, so any sweetener that isn't sugar, honey, molasses, or fruit sugar is suspect.
This isn't a 'me' thing. I remember quite a few people telling me that they stopped diet soda and the weight dropped off them. I also know many people who diet relentlessly and can't lose weight, but they chug liters of diet soda every day. Of course, that part is anecdotal.
More anecdotal evidence: Diet Coke was first released in 1982.
-J