Other factors may muddle the link; people who consume more artificially sweeteners may eat more processed food, for example, which is linked to a higher risk for obesity or heart-related problems.
The team reviewed 37 different studies that involved over 4 lakh people who were followed for nearly a decade. Among these studies, only 7 were randomized controlled trials (the gold standard in clinical research) and those studies involved 1003 people, who were followed for an average of 6 months.
Assistant Professor Dr Ryan Zarychanski said: "We found that data from clinical trials do not clearly support the intended benefits of artificial sweeteners for weight management".
The team found the clinical trials did not show a clear benefit or a consistent effect on weight loss, despite often being promoted for this reason.
"Caution is warranted until the long-term health effects of artificial sweeteners are fully characterized", said lead author Dr. Meghan Azad, whose team at the Children's Hospital Research Institute of Manitoba is also now looking into how consuming artificial sweeteners while pregnant may influence weight gain, metabolism and gut bacteria in children.
"Sweeteners may have adverse effects on glucose metabolism, gut microbiota and appetite control".
Meanwhile, a reanalysis of the 30 longitudinal studies found that people who consumed low-calorie sweeteners on a regular basis were more susceptible to obesity, diabetes, and cardiovascular issues such as high blood pressure and stroke over time.
Ordering a diet soda as a "healthier" choice may be backfiring.
The study highlights the fact that more research needs to be conducted before "the long-term risks and benefits of these products are fully characterized".
Because artificial sweeteners have been associated with health problems, experts have several working theories to explain the link.
NIH pediatric endocrinologist Dr. Kristina Rother, who wasn't involved in the study, said it is a strong piece of work that highlights the need for more and better-designed studies on low-calorie sweeteners. She uses a variety of artificial sweeteners in her coffee, tea, cereal, on bitter fruit, in smoothies and in baking.
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.
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.