Artificial sweeteners, such as those contained in diet drinks, don’t actually help people lose weight, a new Canadian study suggests. In fact, they appear to be linked to weight gain and an increased risk of diabetes.
Dr. Meghan Azad and a team of researchers of the University of Manitoba conducted a meta-review of 37 previously published studies that looked at the diet habits of more than 400,000 people.
The team found no good evidence that regularly consuming artificial sweeteners led to weight loss. In fact, the longer observational studies showed a link between the sweeteners and higher risks of weight gain and obesity, high blood pressure, diabetes, and other health issues.
The full results appear in the Canadian Medical Association Journal (CMAJ).
Azad said what her team was most struck by was the lack of good, rigorous studies on artificial sweeteners.
“Surprisingly, given how common these products are, not many studies have looked at the long-term impact of their consumption,” Azad told CTV News Channel from Lisbon, Portugal.
She noted that only seven of the 37 studies they reviewed were randomized controlled trials (RCTs), and all were relatively short, following participants for a median period of only six months.
The other 30 studies were longer and followed the participants for an average of 10 years, but they were observational studies – a form of research that is not as precise as a controlled trial.
“A lot of the studies we found were observational, meaning they could show a link but they can’t prove a cause-and-effect relationship,” she said.
Among the seven RCT’s, regular consumption of sweeteners had no significant effect on weight loss. From the other studies, the team found that regular use of sweeteners was associated with an increased risk of type 2 diabetes and high blood pressure, and modest increases in weight and waist circumferences.
“What we found was that at the end of the day, from all of this research, there really wasn’t firm evidence of a long-term benefit of artificial sweeteners. And there was some evidence of long-term harm from long-term consumption,” Azad said.
As for why artificial sweeteners seem to be linked to weight gain, not weight loss, Azad says no one knows for sure but there are lots of theories.
One theory is that the sweeteners somehow disrupt healthy gut bacteria. Another theory is that the sweeteners confuse our metabolisms, causing them to overreact to sugary tastes.
It could be that those who regularly use artificial sweeteners over-compensate for the missed calories from sugar, or they could have otherwise unhealthy diets in conjunction with sweetener use.
Azad would like to see a lot more research on the long-term use of sweeteners, in particular studies that could compare the different sweeteners, to see if one is any better than another.
In the meantime, for those trying to cut down on their sugar consumption, Azad says it’s important not to switch from one harmful food item to another.
“I think the takeaway for Canadians at this point is to maybe think twice about whether you really want to be consuming these artificial sweeteners, particularly on an everyday basis,” Azad said, “because really we don’t have evidence to say for sure whether these are truly harmless alternatives to sugar.”
