Artificial Sweeteners Linked To Weight Gain?

The papers were full of it back in July 2017: artifical sweeters linked to weight gain, not weight loss. 

This was the result of a major study by Dr. Meghan B. Azad and colleagues, published in the  Canadian Medical Association Journal, following more than 400,000 people over an average period of 10 years. 

Compelling evidence . . . or is it?

The study was a systematic review and meta-analysis of 37 individual studies.

Of the 37

  • only 7 were randomized controlled trials ( RCT’s ), the gold standard in medical research.
  • the remaining 30 were observational ( prospective cohort ) studies, although they did follow individuals for a decade.

The Results:

  1. “In the 7 included RCTs,  non-nutritive sweeteners had no significant effect on body mass index ( BMI  ) or other measures of body composition. Furthermore there were no other associated secondary outcomes.
  2. The remaining studies showed a modest increase in BMI and waist circumference measurement (belly-fat) over the 10 year period as well as an increased incidence of high blood pressure, diabetes and cardiovascular events.


High quality RCTs provided no evidence of weight gain or loss and no association with secondary factors (heart disease or diabetes)

Observational studies showed some association between the two

If we go with the best evidence, there is no evidence of any effect, good or ill

The other studies showed only an association not a cause-effect relationship: it’s possible that

  • people using sugar substitutes might binge more because they feel they can
  • people whose behaviour puts them at risk of weight gain, diabetes and heart-disease may be more likely to select sugar-free alternatives to compensate for an otherwise unhealthy life-style
  • artificial sweeteners MAY increase hunger by confusing the brain, but the evidence is inconclusive
  • some artificial sweeteners disrupt the balance of healthy gut bacteria ( biome ), but the end-effect is speculative. Additionally, synthetic aspartame and natural stevia are chemically distinct and unlikely to have similar effects on the gut biome

Do artificial sweeteners cause harm?

  • The best evidence says no.
  • The remainder suggests so.

The answer: probably not. But actually, we don’t know.


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