The Skinny Behind Obesity And Artificial Sweeteners

New Research Shows Why Artificial Sweeteners Really Do Cause Weight Gain

Weizmann Institute, obesity study, artificial sweeteners, aspartame, sucralose, saccharine, weight gain sugar substitute link

What’s the real link between artificial sweeteners and weight gain?  Is it something as simple as people who are over weight are more drawn to artificial sweeteners than healthy weight people?  Or do artificial sweeteners actually cause weight gain?   These questions have been puzzling scientists for years.  New research from Weizmann Institute of Science is finally making sense of it all.  And the findings are pretty interesting!

So much of what impacts our health is actually regulated by our gut.  An unhealthy gut can be linked to almost any illness.  There seems to be a link between artificial sweeteners, the bacteria in our gut, and our ability to regulate glucose.  Scientists from Weizmann Institute’s Immunology Department gave mice water that contained aspartame, sucralose, and saccharine in the amounts that would equal human consumption permitted by the FDA.  Another group of mice were given sugar water, and a third group given regular water.  The mice given the water sweetened artificially developed glucose intolerance, but not the other two groups, even the group given real sugar!   They repeated the experiment using different mice and different doses of sweeteners, and still got the same results showing that somehow the sweeteners were inducing glucose intolerance.

Next, the researchers investigated a hypothesis that the gut microbiota are involved in this phenomenon. They thought the bacteria might do this by reacting to new substances like artificial sweeteners, which the body itself may not recognize as “food.” Indeed, artificial sweeteners are not absorbed in the gastrointestinal tract, but in passing through they encounter trillions of the bacteria in the gut microbiota.

The researchers treated mice with antibiotics to eradicate many of their gut bacteria; this resulted in a full reversal of the artificial sweeteners’ effects on glucose metabolism. Next, they transferred the microbiota from mice that consumed artificial sweeteners to ‘germ-free’ mice – resulting in a complete transmission of the glucose intolerance into the recipient mice. This, in itself, was conclusive proof that changes to the gut bacteria are directly responsible for the harmful effects to their host’s metabolism. The group even found that incubating the microbiota outside the body, together with artificial sweeteners, was sufficient to induce glucose intolerance in the sterile mice. A detailed characterization of the microbiota in these mice revealed profound changes to their bacterial populations, including new microbial functions that are known to infer a propensity to obesity, diabetes and complications of these problems in both mice and humans.”


Next the scientists wanted to see if human micro biome function would react the same way as the mice.   They conducted another controlled experiment, using a group of volunteers who did not normally consume artificial sweeteners.  They asked the group to eat and drink artificially sweetened products for a week, then had them get their glucose levels tested, as well as their gut microbes.

“The findings showed that many – but not all – of the volunteers had begun to develop glucose intolerance after just one week of artificial sweetener consumption. The composition of their gut microbiota explained the difference: The researchers discovered two different populations of human gut bacteria – one that induced glucose intolerance when exposed to the sweeteners, the second that had no effect either way. [The scientists believe] that certain bacteria in the guts of those who developed glucose intolerance reacted to the chemical sweeteners by secreting substances that then provoked an inflammatory response similar to sugar overdose, promoting changes in the body’s ability to utilize sugar.”

 Weizmann Institute’s Prof. Eran Segal:  “The results of our experiments highlight the importance of personalized medicine and nutrition to our overall health. We believe that an integrated analysis of individualized ‘big data’ from our genome, microbiome and dietary habits could transform our ability to understand how foods and nutritional supplements affect a person’s health and risk of disease.”
Dr. Eran Elinav: “Our relationship with our own individual mix of gut bacteria is a huge factor in determining how the food we eat affects us. Especially intriguing is the link between use of artificial sweeteners – through the bacteria in our guts – to a tendency to develop the very disorders they were designed to prevent; this calls for reassessment of today’s massive, unsupervised consumption of these substances.”
Source:  Wizeman Institue Of Science


  1. FM says

    Hi, I’m very interested in this. I’m studying developmental psychology and doing a research report on obesity in children, one of the interesting topics I’ve come across is the role of gut flora in obesity. I’ve also read a lot about artificial sweeteners inducing weight gain rather than preventing it. It worries me that more and more we are expecting our younger children to consume artificial sweeteners – sweetened drinks are now banned in Australian school canteens, flavoured milks are encouraged to up calcium intakes but only if artificially sweetened, as are iced teas and softdrinks. This is to prevent obesity – I can’t help but feel it’s a step in the wrong direction. What do you think?
    The link you gave as a source only leads to a generic front page website – please could you provide a link to the actual paper you are quoting? Thank you.

    • Rebecca says

      I agree with you! It’s a step in the wrong direction, and it’s so frustrating because the artificial sweetener can lead to even more health problems.
      I think to get to the study information, I searched “wizeman institute artificial sweetener obesity study” or something like that. Or on their site they may have a search option. =)

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