It’s a well-worn scare meme: The sugar substitutes that permeate our food supply through diet soft drinks or low-cal snack alternatives are as dangerous to our health as plain old sucrose, if not more so. That we broadly label them artificial sweeteners only adds to some people’s already prevalent fear of “unnatural” chemicals, though such a term ignores the growing trend of naturally derived sugar substitutes in the market (Truvia).

But while we’re certain that sweeteners like aspartame don’t contribute to a slew of chronic disorders like lupus, cancer, and multiple sclerosis, that doesn’t mean there can’t still be legitimate concerns about their use. One enduring criticism is that sugar substitutes don’t work as advertised in the real world — they actually make us eat/drink more than we would otherwise, leading to weight gain.

Now, an extensive review published in the International Journal of Obesity this November has sought to address that worry for us. Analyzing more than a hundred human and animal studies, the researchers concluded that using these low-energy sweeteners (LES) as a sugar replacement doesn’t lead to more calorie intake and even offers a small benefit to weight loss attempts. They might even provide a slight improvement over switching to water.


The leading reason behind the theory that LES consumption leads to weight gain has more to do with psychology than it does biology. Namely, it’s the idea that consumers will make up for any caloric losses they obtained by switching to low-cal sweeteners elsewhere in the meal — a diet soda at lunch may lead you to splurge on the supersized fries, in other words. There has even been some evidence of this effect, called compensation, seen in animal studies.

As the researchers note, however, these animal trials often recruit their lab subjects (usually mice) to ingest qualities of LES that no human could consume in a week, let alone a single day, making it hard to extrapolate their results to people. Even there, though, in the 90 animal studies the team looked at, two-thirds either pointed to a small decrease in or neutral effect on energy intake.

And while the researchers did find some evidence of compensation in people, the overall energy intake was still lower in these groups than with those who stuck with their full-calorie counterparts. Whether they looked at longer-term trials (four weeks to 40 months) or short-term studies of a single meal, they saw a slight boost in calorie reduction, even when compared to control groups that substituted water for their daily soda can. “One possible interpretation is that access to LES satisfies a pre-existing desire for sweetness, rather than promoting it,” the researchers theorized as an explanation.

Their findings also fly in the face of another popular belief, reinforced by some animal research, that diet sodas can implicitly trick the body into craving calories by confusing the “sweet” receptors located in our gut. Of course, human diets are a great deal more complex than that of the common lab rat (even if we both do love pizza), and the researchers believe that LES do little to disturb the sweet receptors in people.

The moniker of “diet” attached to many a soft drink, the most popular type of low-cal product, might still be a bit misleading, however. While low-cal sweeteners won’t make you gain weight, their ability to trim the pounds off is likely marginal. When the researchers combined the findings of the three largest population studies they had available to them, they found that one serving of diet soda per day over a 4-year period amounted to losing one-fifth of a pound.

So go ahead and guzzle that diet Coke. Just don’t expect any miracles.

Source: Roger P, Hogenkemp P, de Graaf C, et al. Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies. International Journal of Obesity. 2015.