Many media stories regarding a diet soda study draw conclusions that don't accurately depict the research findings, which were released on Friday.
News articles with headlines that scream "diet sodas make people fat" may attract readers, but the research, published in the American Journal of Public Health, says only that overweight and obese people don't end up eating fewer overall calories than those who drink sugary beverages.
They tend to make up for the fewer calories in their drinks by eating more solid calories. Therefore, they're not any further ahead or behind than if they drank sugar sweetened rather than sugar free drinks.
The authors write, "Overweight and obese adults drink more diet beverages than healthy weight adults and consume significantly more solid food calories and a comparable total calories" than those who drink sugar sweetened beverages. Since these individuals consumed a "comparable" number of total calories, diet sodas don't seem to help or hinder weight control in heavier adults.
The study, which used data from the nationally representative continuous National Health and Nutrition Examination Survey, also found that healthy individuals who consumed diet sodas ate significantly fewer daily calories overall. Some may infer from this conclusion that some normal weight people could become overweight if they drank sugar sweetened soda rather than diet. Also, perhaps some people could have avoided becoming overweight had they switched to diet sodas before packing on extra pounds.
The study doesn't draw these two specific conclusions about what could happen to normal weight people if they switched from diet to sugar sweetened sodas, but it also doesn't say that diet sodas make people fatter.