More and more people are cutting back on sugar to try and lose weight and improve their health. One of the easiest and relatively painless ways to do this is to use artificial sweeteners such as aspartame, sucralose and stevia in place of sugar. This easy fix comes at a price, however. Emerging evidence suggests artificial sweeteners can slow down metabolism, increase appetite and disrupt the population of bacteria in the gut, called the gut microbiome.

In fact, artificial sweeteners can bring on weight gain and lead to serious health problems in the long run, a new Canadian study finds.

Many people use these products, assuming they are the healthier choice, a good alternative to sugar, and helpful for using weight or at least preventing weight gain, Meghan Azad, lead author on the study, told TheDoctor. So it's a surprise to learn the sweeteners may cause health problems.

“Whether or not they have calories, the use of sweeteners makes us crave other sweet things, and we just eat more calories anyway.”

The evidence suggests artificial sweeteners may be harmful. And while the research is not conclusive, said Azad, so many people use these sweeteners, or consume artificially sweetened foods and beverages regularly, it is important to determine what kind, if any, health problems the products may pose. “It’s important to have more research, so we can make recommendations about the long-term use of these products,” she said.

Azad and her team from the University of Manitoba and the Children’s Hospital Research Institute of Manitoba systematically reviewed the findings of 37 studies that followed over 400,000 people for an average period of 10 years. They found artificial sweeteners had no consistent effect on weight loss. At the same time, results of longer observational studies showed an association between use of artificial sweeteners and an increased risk of weight gain and conditions such as diabetes, obesity, heart disease and high blood pressure.

You really shouldn’t be sweetening everything, even with artificial sweeteners, because that just supports development of a sweet tooth, said Azad. “Whether or not they have calories, the use of sweeteners makes us crave other sweet things, and we just eat more calories anyway.” The healthiest choices would be water, black coffee or unsweetened drinks.

People should think more carefully about whether they want to be consuming these products on a regular basis, Azad cautioned. “Think about whether that is really a choice you want to make, given the evidence, and don’t make the assumption it is a harmless and totally healthy alternative.”

Azad and her team are currently conducting a study looking at the effect of artificial sweetener consumption by pregnant women on the weight, metabolism and gut microbiome of their babies.

Future research will need to examine the specific effects of different artificial sweeteners and look at a broader range of artificially-sweetened foods. Many long-term observational studies were begun when fewer sweeteners were available. That is both a strength and a limitation, Azad explained. A 30-year observational study gives researchers a lot of data, but because the study started so long ago, it did not ask about the newer products like stevia, for example.

These earlier studies tended to simply ask, ‘Do you drink diet beverages and how often?’ Azad noted. “Now we know these sweeteners are found more increasingly in foods, such as yogurts. So we are not really capturing the consumption patterns very well.”

Finally, research needs to monitor the effects of sweeteners in small children and infants. National nutrition surveys show that about 25 percent of children are consuming artificially sweetened foods and beverages on a regular basis. That is a huge number of children, and we don’t really know the long-term impact in that age group, Azad added.

The study is published in CMAJ, The Canadian Medical Association Journal.