The new year has arrived! Naturally, everybody everywhere has pledged to start a new diet and join their local gym.
Following this temporary nationwide shift in diet and exercise habits, every major news outlet is running silly advice articles promising readers the weight loss results they want if they tweak their habits in just the right way.
Most of this advice is typical pop-science boilerplate, unworthy of anyone's valuable time. But there's one bromide I've seen repeated more than usual this January: the claim that artificial sweeteners will make you fat.
I've seen everyone from HuffPo health writers to bona fide nutrition experts smugly asserting that your diet soda will stunt your weight loss effort and even push your weight in the wrong direction.
With that eloquent thesis laid out, we're going to go through every fallacious reason people give for swearing off artificial sweeteners, and we're going to rely on the best science that's available.
Artificial sweeteners stimulate your appetite
If you're a fly. None of us are flies, so we could move on to more interesting facets of this debate. But disingenuous health writers also like to point out that overweight, diabetic people are more likely to drink diet soda than slimmer, metabolically healthy people. That's got to tell us something about the negative effects of sugar substitutes.
Of course, we could discount every diet ever conceived as ineffective since only fat people and diabetics go on diets to slim down. Or as the authors of a recent PLoS One article put it, " ... findings from observational studies might be biased by residual confounding ... as overweight/obese people are more likely to consume [artificial sweeteners] in an attempt to control weight." This didn't stop the authors from cautioning against consuming sugar substitutes, of course.
Some dieters do gain weight when they switch to sugar substitutes, but that's because they eat more than they otherwise would, assuming they can get away with an extra slice of pizza because they're abstaining from Code Red Mountain Dew. Though that's no reason to blame artificial sweeteners for stimulating your appetite.
According to this study, low blood sugar predicted a lack of self-control in a series of tasks that involved regulating emotion and suppressing negative thinking. Consuming a sugary drink helped participants in this study perform better on subsequent self-control tasks.
The paper is interesting and underscores the importance of properly regulating blood sugar, a point stressed by advocates of low-carb and paelo diets, mind you. However, the geniuses at The Conversation took this as evidence that sugar substitutes impair self-control since they didn't spike blood glucose the same way the sugary milkshake used in the study did.
It's widely accepted that high blood sugar is the primary cause behind weight gain. Therefore, you should obviously avoid sugar substitutes because they don't spike your blood glucose like sugar does. Think through that a few times, then read on.
Artificial sweeteners are full of chemicals
I won't patronize anyone by smugly harping on the obvious retort that everything is full of, or rather composed of, chemicals. But this objection to artificial sweeteners is usually grounded in the ambiguous claim that the especially nasty chemicals in your diet Coke somehow damage your metabolism by harming your gut health.
The best support that can be mustered for this link between poor gut health and artificial sweetener consumption is this paper in Nature, in which the researchers altered the microbiota of mice by feeding them saccharine and increasing their glucose intolerance. The problem, though, as the researchers state is that "... human individuals feature a personalized response to [artificial sweeteners], possibly stemming from differences in their microbiota composition and function..."
The authors go on to argue that the changes they saw in these mice likely occur in humans as well, however, because they found "significant positive correlations between [artificial sweetener] consumption and several metabolic-syndrome-related clinical parameters ..." To find that correlation, they relied on self-reported data around artificial sweetener consumption. Of course we all know how awfully unreliable food frequency surveys are.
These limited results leads us on a search for better studies, preferably those in which the researchers didn't study rodents and then infer that people have the same reaction to artificial sweeteners.
A few papers of this sort have been published, but the results are mixed. Some studies show no effect whatsoever, others indicate that sugar substitutes can help people lose a modest amount of weight. None implicate artificial sweeteners as culprits in causing weight gain.
The naysayers handle this as expected. They claim that dieters who switch to diet soda lose less weight than dieters who drink only water, though the difference is clinically insignificant--only 2.6 lbs in the cited study. If you're severely overweight or obese, losing two pounds won't do much for your health, and it's certainly less than you had in mind when you thought up your weight loss resolution.
I hope you see the theme here. The research returns an inconclusive result or suggests--as does common sense-- that sugarless, calorie-free sweeteners aid weight loss. Yet again and again we're told to avoid sweeteners.
One point worth acknowledging is that everyone is indeed slightly different. Some people stuff their faces with junk food, for instance, and maintain the slender figure everyone else wants. So it's at least possible that some people gain weight when they eat sugar substitutes while others don't. But exceptions prove rules more often than they refute them.
Let me borrow a cliche from psychology and point out that humans aren't individually all that special. Being the narcissists we are, we like to think that we're the special case that bucks the trend. But that's usually hubris. There'd be no point in studying nutrition if everyone was so different from one another.
What seems most reasonable given the evidence we've discussed is this: there is some small sliver of the population that doesn't react well to sugar substitutes. This is true of vaccines, anti-depressants and a variety of other medical interventions. That fact, however, is not a good foundation for a blanket condemnation of sugar substitutes.
So as we head into another year, let's quit wasting everyone's time with speculative suggestions and make the changes we know will help us lose weight. There are certain foods that should be avoided generally, but Splenda probably isn't one of them. Unless someone wants to provide some better evidence.