Diet Soda's Dirty Little Secret: O Calories- Infinite Problems.

A question was posed to me that on first sight seemed like it was going to be a really simple one to answer, but as I got into it it grew to be more and more complicated.  The question was about diet soda.  Are they OK to drink occasionally?  What harm can they really do since they are 0 calorie and have no actual sugar in them?  The answer is A LOT!  Now that being said will drinking a diet Coke kill you? Maybe-maybe not.  It depends on who you are and what you are trying to achieve.  In the last post we discussed how soda and diet sodas can prevent calcium absorption, so we'll leave that one alone and strictly talk about the effect artificial sweeteners and diet soda have on the rest of you.
There is plenty of anecdotal evidence out there showing that people who are eating severely low calorie diets still don't lose weight or even gain weight when they consume large quantities of artificial sweeteners in diet sodas.  This is strange because a severe enough caloric deficit should, regardless of food quality, eventually causes weight-loss.  So whats the problem here?  What are artificial sweeteners?
Well without getting to nerdy (I mean if you want me to all you have to do is ask nicely and compliment my eyes and I will), most artificial sweeteners are a smart people tricky way of getting us to taste sweetness without the glucose/fructose that should go along with it.  In some that means taking molecules of sugar and changing them ever so slightly so that our bodies won't recognize them.   Others are modifications of amino acids made to trigger a sweet taste in your mouth.   One of them is a molecule of sucrose with a chlorine attached to it (yes you are consuming chlorine  Either way this causes problems down the yellow brick road that is your hormonal signaling for your digestive system.
These artificial sweeteners make your tongue the boy who cries wolf.  Your tongue tastes sweet so it yells down, "Help! We got some glucose coming in!".  Your body responds by producing insulin to take care of the excess blood sugar it thinks is coming in.  Here is where the shit can hit the fan because there isn't going to be any more raise in blood sugar.  So whats all that rowdy insulin suppose to do?  It does it's job and yanks sugar out of the blood, that your body actual needs to stay there.  This causes your body to start signaling for more sugar/food to replace the stuff it mistakenly took out. This causes you get hungry again or start craving another diet soda.  It really is a great market these diet soda people have, drinking one makes your crave another which makes you crave another.  Sounds like a drug addiction doesn't it? (PSSSTTT That's cause it is).  This is the reason why most people find these things so hard to stop drinking.  They are in fact addictive.  Here's a nice little quote from a super smart guy named Kurt Harris MD of PaNu blog :

"There is some evidence there may be a physiologically significant insulin response with artificial sweeteners just due to the sweet taste- even if small, the corresponding drop in blood glucose may be exaggerated by the fact no glucose is consumed - when blood glucose drops, other hormones rise in response, stimulating your appetite. Of course insulin itself drives fat storage and decreases insulin sensitivity, so there may be direct unhealthy effects as well."

http://www.paleonu.com/panu-weblog/2009/6/17/what-about-diet-soda.html

And this leads to another problem with these sneaky sweeteners.  Your body can't use all the insulin produced so now you have a bunch of free floating insulin.  This is bad. This is one of the hypotheses as to the cause of insulin resistance.  This is one of the main and most prevalent causes of metabolic syndrome.  This explains why those people on severely low calorie diets still can't lose weight and can continue to gain weight.
Here's a nice little study to read if you want to get down and nerdy with me:  Whats interesting is that in the subjects with Non-Alcoholic Fatty Liver Disorder, 80% of them consumed excessive amounts of soft drinks- 40% of those soft drinks being Diet.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2661299/
Back to the original question:  Can I drink diet soda every once in a while?  I would say try not to, especially if you are overtly insulin resistant and are in the process of trying to lean out to improve performance.  If you are as lean as you want to be, fat adapted, not eating any grains, legumes, or dairy, and its only once in a very long while (that doesn't mean weekly) when you want to get down with your bad self and have a rum and diet (or just have a NorCal Margarita), go for it.  Enjoy life but understand the problems that come along with drinking artificial sweeteners.
I tried to keep it as painlessly nerdy as I possibly could guys, even though I'm pretty sure most of you guys will now start reading this as a sleep aid every night, but I hope this helps.  And as always if you cannot pronounce whats in it don't eat it.