Diet soft drinks are associated with the worst kind of weight gain, new research has suggested.
Those who consumed artificially sweetened soda put on almost triple the belly fat of those who did not, the study reported, although direct causation was not proven.
Between 1992 and 2004, test subjects who drank zero-calorie beverages gained almost six centimetres more around their waistlines than those who did not drink them at all, the study published in the Journal of the American Geriatrics Society found.
It may be that these diet drinks trigger “a behavioural issue” by tricking us into eating more junk because we feel guilt-free, a leading nutrition academic explained.
“If there is a real association, it’s because people’s behaviour has changed because they’ve consumed the artificial sweeteners, so they think they can get away with a bit more solid stuff,” University of South Australia Professor Peter Clifton said.
This theory is “certainly possible”, although he noted that “reverse causation” could be the more likely explanation, by which he meant that overweight people may choose diet soft drinks, and not the other way around.
It may not be bacteria or insulin spikes
Other researchers have suggested the drinks may either kill fat-preventing bacteria in the stomach or unleash the same diabetes-linked chemicals in the body as actual sugar, but Professor Clifton refuted both these theories.
No-calorie drinks “definitely don’t” trigger the same insulin response as sugar, and it is “pretty implausible” that they kill helpful bacteria, although their influence on eating habits is worth investigating, he said.
However, the results do clash with previous intervention studies, which are a type of research considered to be more reliable than this latest study.
Australian Beverages Council CEO Geoff Parker told The New Daily that the healthiness of diet drinks should be weighed up by looking at the science as a whole, not just one study.
“This is one small drop in the ocean of scientific research around artificial sweeteners,” Mr Parker said.
“The majority of research and the totality of evidence out there clearly shows that diet soft drinks in particular can be an effective tool in managing weight, so we take this particular study with a grain of sand.”
The real reason to quit
Neither this nor the latest study definitely proves that artificially sweetened drinks make you fat, but there is a proven reason to avoid diet soda altogether.
Soft drinks are so acidic that regular consumption can damage your smile.
“They’re bad for teeth, no doubt about that, even when they don’t have sugar,” Professor Clifton says.
“They’re better than full-sugar drinks, but they’re not benign in terms of teeth.
“Better not to drink anything other than water. That will look after your teeth maximally, but if you want to drink something sweet, then artificially sweetened is better than sugared.”