Can Artificial Sweeteners Make You Gain Weight?

Psychologists Susan Swithers and Terry Davidson at Purdue University reported today in the journal Behavioral Neuroscience that a study they did on rats showed that those fed yogurt sweetened with saccharin gained more weight than those fed yogurt sweetened with sugar. The rats fed saccharine ate more, presumably because the sweetness of the saccharine stimulated their taste buds to tell their brains to signal their stomachs to expect more calories in the form of sugar than they actually received.

When I first heard this on MSNBC today, I thought that the network covered this story in a silly fashion since they jumped from reporting the results about saccharine fed to rats to asking whether the drinking diet soda or eating other foods that are artificially sweetened might cause weight gain in humans.  I found this silly because my immediate reaction was to think that humans who drink and eat foods with sugar substitutes are doing so intentionally because they want to either lose weight or avoid gaining weight; in contrast the rats had no such goals and presumably ate until they felt satisfied.  My attitude was that people would apply some will power and resist the urge to eat more regardless of any crossed wires between their brains and their stomachs.  I suppose I wasn’t really being realistic.  If people had as much will power as I was supposing, we wouldn’t have so many obese people here in the United States.

One thing MSNBC had failed to mention which Scientific American’s website did was that Dr. Swithers and Dr. Davidson pointed out that their results are in line with recent studies in people that demonstrate that people who consume diet soda are more susceptible to a collection of risk factors for heart disease and diabetes known as metabolic syndrome.  For instance, a paper published in the America Heart Association’s journal, Circulation, indicated that the risk of developing metabolic syndrome was 34% higher for people who drank one can of diet soda each day.  So, there actually is some evidence to suggest that the findings in rats might also hold true in people.

I think it would be interesting for the scientists to study how rats and people respond if fed various mixtures of sugar and saccharine or other artificial sweeteners.  When I drink diet soda, I usually drink it with something else, sometimes even with cookies or other sweet foods that contain sugar.  I drink diet soda rather than regular soda because I actually like the bitter nuance of aspartame in diet soda and figure that I don’t need the extra calories that regular soda would have.  In contrast, I don’t really like low-fat or artificially sweetened cookies.  Assuming the aspartame on my taste buds does send some signal to my brain saying that my stomach is going to receive some sugar, is the amount of sugar in the cookies or other food sufficient to meet my stomach’s expectations?  Or would the brain still perceive a shortfall of sugar in comparison to its expecations?

Along these lines, I wonder if the observed linkage between diet soda and metabolic syndrome is primarily driven by drinking diet soda without food — maybe a can of diet soda drunk by itself stimulates hunger that leads to additional eating afterwards.  Determining the exact circumstances under which consumption of artificial sweeteners stimulates extra eating is clearly very important.  Artificial sweeteners clearly have value if people can consume them without being stimulated to eat more than they otherwise would.  If it turns out that artificially sweetened foods should be mixed with regular food to avoid confusing the brain, then it will be important to determine the ideal ratios so that people can then minimize their total caloric consumption.

Tags: artificial sweetners, gain weight, metabolic syndrome, saccharine, Swithers and Davidson, weight gain