Diet Drinks cause weight gains?!

Diet drinks pose a paradox.  Though they are sweetened with a form of sugar that the body cannot digest and therefore have no calories, as recently mentioned in Science News some recent studies seem to show that people consuming diet drinks gain more weight than those drinking regular sodas.  How can this be?  

It seems the explanation lies in how the body tries to self-regulate calorie intake.  We know now that the brain tries to keep track of the number of calories we eat on a daily basis, and then tells us when to eat more or stop eating for the day.  

The process through which this takes place begins in the mouth.  When food arrives in there, sensors there can tell by taste stimulation that calories have arrived.  The mouth then signals the stomach to get ready to go to work.  

When food arrives in the stomach, it tells the brain about how many calories actually arrived.  The problem comes when we consume diet sugar or oils, such as Olestra, Saccharine, aspartame, Splenda, and Sorbitol.  The mouth tastes calories but the stomach finds none, and sends a “no calories here” message to the brain.  

Being a quick learner, the brain learns that the taste of sweetness in food is associated with no calories, and therefore disregards all other calorie intakes of those flavors when keeping tally of the total calorie ingestion for the day.  The result is that ALL of the fat or sugar you then eat may then be disregarded, and the brain makes you eat more of other types of calories to make up for it and obtain the necessary daily amount.  The net result is that people consuming these ‘diet’ artificial oils and sweeteners tend to gain more weight than those eating the real version.

It isn't that there is something magical about diet sweeteners, but that the brain ends up leaving the "hungry - eat more!" appetite switch in the "on" position longer.  More food ends up being eaten, and weight is gained.