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Big shock: drinking diet soda is associated with wider waistlines, study finds

A recent study in the Journal of the American Geriatrics Society found a “striking” correlation between the consumption of diet soft drinks and expanding waistlines among older adults.

A recent study published in the Journal of the American Geriatrics Society has found a “striking” correlation between the daily consumption of diet soft drinks and an expanding waistline among older adults.
REUTERS/Carlo Allegri

As the Washington Post reported earlier this year, sales of diet sodas in the United States peaked in 2009 at $8.5 billion. Since then, sales have plummeted by 20 percent, and they are expected to fall another 10 percent by 2019.

That’s a remarkable fall-out-of-favor for a product that is heavily marketed and ubiquitously available.

One reason American consumers are losing their taste for diet soda is due to an increasing number of scientific reports about the negative health effects of artificial sweeteners, including research that has begun to link diet sodas  — like their sugary twins — to the development of belly fat. Excessive belly fat, as other research has made clear in recent years, is associated with a host of health problems, including an increased risk of diabetes and heart disease.

A recent study published in the Journal of the American Geriatrics Society adds to this growing concern about diet soda. It has found a “striking” correlation between the daily consumption of such soft drinks and an expanding waistline among older adults.

Study details

For the study, a team of University of Texas researchers followed people aged 65 and older for an average of nine years. The participants had a variety of measurements taken, including weight, waist circumference and fasting blood glucose levels, at the start of the study and at three follow-up sessions. They were also asked questions about their physical activity and their diet, including their consumption of diet soda. The study began with 749 participants, although only 375 completed all three follow-up sessions.

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Based on their soda consumption, the participants were divided into three groups: non-users of diet soda, occasional users (less than one diet soda a day, but more than zero), and daily users (more than one diet soda a day).  At the start of the study, 88 percent of the daily-users were overweight or obese, compared with 81 percent of the occasional users and 72 percent of the non-users.

When the data from these three groups were compared, the researchers found that the average waist circumference gain for the daily users of diet sodas was almost triple that of non-users. Specifically, the non-users gained an average of less than one inch around their waists over the nine years of the study compared to almost two inches for the occasional users and about three inches for the daily users.

The findings held even after controlling for several possible confounding factors, such as physical activity, ethnicity, diabetes and smoking.


This study was an observational one, so it can suggest only a correlation between the regular consumption of diet soda and increased belly fat; it can’t prove cause and effect. It’s possible that factors having nothing to do with the diet soda led to the differences in waistline circumference among the groups. Indeed, a study published last year found that not only do people who are overweight and obese drink more diet soda than their normal-weight peers, they also consume more calories from solid foods.

Still, as the findings from both that study and this current one underscore, whether or not drinking diet soda contributes directly to excess body fat, it certainly seems to do little, if anything, to help people maintain a healthy waist circumference.

If you want to keep your body fat down, try a much less expensive and even more accessible alternative: water.

You can download and read the current study in full on the website for the Journal of the American Geriatrics Society.