The review of 37 studies suggests the use of so-called non-nutritive sweeteners could be linked to weight gain and other undesirable outcomes like high blood pressure and type 2 diabetes.
It says more people are eating and drinking artificial sweeteners like aspartame, sucralose, and stevia.
However, these studies don't prove that the health problems are caused by the sweeteners.
There's no evidence that artificial sweeteners alter the way the body processes sugar, she noted, and some research has shown that sugar substitutes do not make a person crave candies more.
The sweeteners, such as saccharin and aspartame, are used in thousands of diet products including drinks, desserts, ready meals, cakes, chewing gum and even toothpaste. Furthermore, in most observational studies, adjustment for variables related to adiposity attenuates or diminishes the observed relations, leading to no significant associations anymore. Nonnutritive sweeteners and cardiometabolic health: a systematic review and meta-analysis of randomised controlled trials and prospective cohort studies.
Numerous clinical trials this study drew on didn't align closely with the way people consume such sweeteners in the real world - for instance, trials generally give subjects diet soda or sweetener capsules, while ignoring other sources, such as food.
"We found that consumption of nonnutritive sweeteners was associated with modest long-term weight gain in observational studies", the study authors found.
Both types of studies have their pluses and limitations. Some of the trials, for example, compared people who drank artificially sweetened beverages to people who drank water.
But those those looking for weight loss help in the short term did not appear to benefit either.
Many argue that artificial sweeteners are a large contributing factor to increases in bodyweight and poor control of blood sugars. But they did not find concrete proof of causation. Swapping sugary drinks for diet drinks that contain artificial sweeteners may condition the body to expect calories, which makes people feel hungrier. In fact, the dosages used in the 2005 study, if applied to human subjects, would have required the equivalent of a daily intake of over 2000 cans of diet drinks, a dosage which, in humans, is too unrealistic to be considered a legitimate health risk.
"I think that the main takeaway is really just that we need more understanding of what might be going on physiologically", she said.
Another possibility is that our bodies have evolved to metabolize sugars in a way that's triggered not by calories or the sugar molecule but by the perception of sweet taste. She says diet soda "produces physiological responses - increasing metabolism and releasing hormones - to anticipate the arrival of sugar and calories".