While artificial sweeteners have previously been touted as an excellent way to replace sugar in your diet and help with weight loss, they have in recent years been found to impact our biology in ways that may have adverse effects on our metabolism. Rather than helping in a quest for weight loss, is it possible that sweeteners could actually cause weight gain and metabolic disease?
A recent systematic review and meta-analysis was recently published in the Canadian Medical Association Journal, which collected the currently available evidence to try to answer this question and received worldwide attention in doing so. They included 37 trials (including 7 randomized controlled trials and 30 cohort studies), looking at a total of over 400,000 individuals (about 1,000 of whom were in the randomized studies).
In their analysis of the randomized controlled trials, over a median follow up of 6 months, they found no significant effect on body mass index (BMI) or measures of body composition. So, use of sweeteners did not result in weight loss, but there was no weight gain seen either.
In the cohort studies, over a median follow up of 10 years, they found an increase in weight, BMI, and waist circumference, and a higher incidence of obesity, metabolic syndrome, type 2 diabetes, high blood pressure, stroke, and cardiovascular events.
So overall, none of the evidence assessed showed a benefit to weight, and the observational data suggested adverse effects of sweeteners on weight and health – none of which is good news. And why is there a difference in conclusions between the randomized trials versus the observational (cohort) data?
Well, it’s possible that the randomized trials were not long enough or big enough to show a negative impact on health, and that if they had been longer trials, perhaps results would have been different.
On the other hand, observational (cohort) data does not give us as trustworthy of an answer to any research question, because the results can be muddied by other factors. One concern is that these data may be confounded by ‘reverse causation’ – meaning that people with obesity, or those more prone to develop obesity (eg family history of obesity) are more likely to use sweeteners to help manage their weight (rather than the sweeteners being the cause of weight gain).
Either way, there is research to suggest biological mechanisms by which sweeteners could have an adverse impact on our metabolic health, particularly in relation to changes they induce in our gut bacteria, as well as our neurobiological response to these chemicals. Further research is clearly needed to better understand their effect on our health.
Remember also that there is no doubt that excess sugar consumption is associated with weight gain and all of the above metabolic complications – so swapping sugar back in is not the answer either.