It might sound a little iffy but it has been demonstrated with diet pop:
When drinking sugar-free diet pop for the first time, the taste of sugar can elicit insulin release.
The key to respondent conditioning (think Pavlov) is that the taste of sugar precedes the unconditional stimulus of sugar in the gut (i.e. it is predictive of signals that sugar in the gut is about to occur). As a result, the taste of sugar comes to elicit insulin release apart from sugar in the gut.
The key is that the conditional stimulus (taste of sugar) signals or reliably precedes the unconditional stimulus (sugar in the gut).The taste of sugar is a conditional stimulus because it elicits insulin release by the pancreas conditionally, that is, dependent upon the relationship in which it signals the unconditional stimulus (sugar in the gut).
Whereas sugar in the gut is the unconditioned stimulus because it unconditionally elicits the insulin release, that is, this relation does not depend upon the learning history of the organism.
Therefore, because there is no sugar from the pop to digest, you may feel weak because the insulin produces a drop in your existing blood sugar level. Although this effect is very temporary.
It is quite possible that a similar effect could occur through stimulation olfactory receptors