Is Diet Soda Bad For You?

I have been asked questions about the safety of diet soda and artificial sweeteners on many occasions so I thought I’d do a little research to educate myself and others on the issue.  Before reading further you should read a prior post on my general approach to deciding whether something is ‘good for you’ or ‘bad for you’ (Click here).   What follows is a brief overview of what I learned about artificial sweeteners and how they may affect weight gain.

The History

Artificial sweeteners were discovered by accident in the late 19th century by some brave scientists.  This was back when men were men and scientists were stupid.  One of the methods these geniuses used to test out their chemicals in the lab was by tasting them.  I have no evidence but I’m sure this came about through a dare.  Saccharin the chemical of the popular Sweet N’ Low was discovered this way by Constantine Fahlberg.  Initially saccharin was a specialty item for diabetics but with the rationing and shortages of World War II, sugar substitutes became an important commodity.  This was followed by the boom in esthetic desire for a slimmer figure.  All this resulted in a steady rise in demand.  As demand increased, more and more products were developed.

Cyclamate was discovered in 1937 by Michael Sveda and was combined with saccharin frequently.  In 1965 James Schlatter discovered aspartame which was marketed as NutraSweet.  In 1967 Karl Clauss discovered acesulfame potassium.  The most recent discovery was in 1979 when Shashikant Phadnis discovered sucralose (Splenda) which is very similar in chemical structure to regular table sugar (sucrose).  These sweeteners are everywhere.  As I look at the ingredients of the Dr. Pepper 10 I’m drinking now, it containes saccharin and acesulfame potassium.

The Controversy

The controversy of the safety of these products came about in the late 60s when cyclamate was associated with an increased risk of cancer in rodents.  This was really bad news for the rats, especially the fat ones.  Guilty by association, saccharin was slapped with a health warning as well by the government as well even though there was no evidence that it caused harm in animals or humans.  Subsequent studies found that the link between cyclamate and cancer was weak and only in rodents and no other species.  In fact there was a study of rats in Canada where one group was given the equivalent of 37 diet sodas a day.  This group developed more cancer.   What you didn’t read on the natural medicine propaganda sites was that this group also lived longer.  Any animal that lives longer has a higher risk of cancer.  Regardless, the warnings were appropriately removed in 2000.  All of the newer artificial sweeteners undergo rigorous safety testing by the FDA before approval and have never been associated with any negative health affects.  The bottom line is that these sweeteners are safe.  What’s not safe is sugar which has been associated with numerous health risks and premature death.

Do Artificial Sweeteners Cause Weight Gain?

When you think about it, it would make sense that switching to artificial sweeteners which have essentially zero calories would help with losing weight.  The research unfortunately is a bit more complicated than that.  There have been several large prospective studies (not blinded randomized controlled trials) that have actually linked high consumption of artificial sweeteners to weight gain.  Most studies, however, indicate that aspartame reduces food intake and may assist with weight control.

As for the studies, that associate artificial sweeteners with weight gain, it is quite possible that patients who use artificial sweeteners compensate with eating more calories elsewhere (I got the Diet Coke so I could eat the supersized fries…).  This is supported by blinded and randomized studies.  When people are given a calorie restricted diet and they don’t know if they got real sugar or an artificial sweetener, weight loss is unaffected.  When the people are told they are getting the artificial sweetener they have been shown to increase their calorie consumption.

Do Artifical Sweeteners Increase Appetite?

It has been shown that sweet tastes, whether from sugar, corn syrup, or artifical sweeteners, will increase appetite.  There is some evidence, however, that the artificial sweeteners may increase appetite more than regular sugar.  Why this is the case is not clear.  It may be that when the brain thinks it’s getting sugar (based on taste) and it gets nothing (based on calories), it triggers the appetite centers of the brain.

Interestingly, other data has shown that artificial sweeteners don’t trigger the reward pathways the way the good stuff does (for more on the reward pathways check out these posts – On Crack and Ice Cream part 1 and part 2).  Imaging studies have shown that the reward pathways that are triggered by sugar are not triggered by sucralose.    Finally, all sweet taste, artificial or natural, can train flavor preference and increase cravings for more sweets in the future.  This was not to a greater extent in either group.

The bottom line

It is not at all clear that artificial sweeteners lead to either weight gain or loss.  It’s confusing because the data is conflicting.  More and better research is needed.  Artificial sweeteners may lead to changes in your brain that increases appetite and sweet cravings, but it may not.  Further, if you are getting a significant amount of calories per day from sugary products, switching to artificial sweeteners could help a great deal.

Here are my recommendations:

Coming off of sugar cold turkey may be too difficult in which case substituting the artificial sweeteners may ease the crash.  If switching to artificial sweeteners completely does not help, it may be that your appetite is still stimulated and decreasing your sweet intake from all sources, artificial or otherwise, may be the most successful way of decreasing your caloric intake and helping with weight loss.  Either way, if you like your Diet Coke, it’s perfectly safe.  Don’t believe the hype.

Sources:

• Q Yang.  Gain weight by “going diet?”  Artificial sweeteners and the neurobiology of sugar cravings.  Yale Journal of Biology and Medicine 2010; 83:101-108
• SD Anton, CK Martin.  Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels.  Appetite. 2010; 55(1): 37–43.