This research is bad news for anyone choosing diet soft drinks to help their waistline.

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A new study published this week in the Journal of the American Geriatrics Society suggests that drinking diet soft drinks could be the reason for increasing waistlines in older people.

The study, which included more than 700 participants, monitored the progress of people aged over 65 over a nine year period. During that time, researchers noted that people who elected to consume diet soft drinks had, on average, a waistline three times that of participants who never consumed diet beverages. More so, occasional diet soft drinkers had waistlines more than double that of those who abstained.

Related: 3 ways to work out how much food you should be eating.

It’s interesting to consider why this could be. Previous studies into the affects of artificial sweeteners have noted that mice used in trial situations developed lesions on the brain after being fed the unnatural sweeteners. (Post continues after gallery.)

This part of the brain happened to be the one that regulates the “I’m full, stop eating” feeling. Therefore, mice who had developed the lesions were more likely to consume more food. Apparently, it could be a similar case for humans.

“The sweeteners could boost weight gain by disrupting the way the body processes sugar, making people more hungry,” says Sharon Fowler, author of the study.

Researchers involved in the trial also noted that the reason for participants' weight gain could also be circumstantial. Fowler told health news that a possible reason for weight gain in some diet soft drinkers could be those “who had seen themselves increasing in weight over the past five to seven years and decided they need to do something about it,” therefore electing to consume diet drinks rather than full calorie.

Keep in mind that the study used participants over the age of 65, typically a group where weight gain and cardiovascular disease is already at an increased risk.

Related: Mia Freedman: “What really goes into my green smoothie.”

Are you a diet soft drinker? Does this change things for you?