The study found that mice who had aspartame-laced water and ate a high-fat diet (HFD) gained more weight than mice who had pure water but also ate a HFD. All mice on HFD gained weight, though.

It also found that mice who eat a nutritionally balanced diet did not gain more weight whether or not they had aspartame.

We already know that people who are eating HFDs and hoping that diet soda will magically cause them to lose weight are wrong.

But, it is possibly useful to know that aspartame may have a confounding effect when combined with a high-fat diet.