People who are into dieting know that artificial sweeteners are better than sugar, but it seems to be wrong in some cases.
Researchers at the University of Minnesota Medical School and School of Public Health conducted a study to learn about how the things we eat and drink might affect our risk of heart problems.
They focused on artificial sweeteners like aspartame and saccharin, which are often used in sugar-free products.
For 20 years, they studied people's diets and found that those who consumed these artificial sweeteners regularly had more fat stored in their belly and in their muscles.
This extra fat can be a risk factor for heart issues.
Surprisingly, one common artificial sweetener called sucralose didn't seem to have the same effect on fat storage.
The study's results challenge the advice from groups like the American Diabetes Association and the American Heart Association, which suggest using artificial sweeteners to replace sugar.
The researchers say we might need to think about different ways to make our food and drinks sweet without using these artificial sweeteners because they could have health consequences.
The World Health Organization has also warned about the potential risks of aspartame, so this study adds to the concerns.
The researchers believe more studies are needed to fully understand how artificial sweeteners might be linked to extra body fat and to figure out how our eating habits affect our health.