In March of 2015, researchers at the University of Texas Health Sciences Center published findings showing that in people age 65 and older, regular consumption of diet soda is associated with increased abdominal obesity. Better known as belly fat, abdominal obesity is associated with a higher risk of diabetes, cardiovascular disease, some types of cancer and premature death.
A total of 749 Mexican-American and European-American seniors enrolled for the study between 1992 and 1996. At the third follow-up, there were only 375 surviving participants. At the outset, the researchers gathered information about the participants’ diets, exercise routines and other lifestyle habits and recorded their height, weight, and waist circumference. Those measurements were repeated at points throughout the 9.4 years the study was in progress.
Results showed that participants who drank diet soda daily increased their waist circumference by 3.16 inches over the duration of the study compared to waist size increases of only 0.80 inches for people who didn’t drink diet soda and 1.83 inches for those who drank it occasionally. The researchers warned that the increased waist circumference seen among the individuals who drank diet soda could increase the risk of metabolic syndrome and cardiovascular disease and urged them to curb their consumption.
We don’t know what it is about diet soda that causes the problem. Sharon Fowler, M.P.H., who led the investigation, was quoted in news accounts as suggesting that the highly acidic nature of diet sodas could distort the balance of gut bacteria, affecting how we digest and metabolize food.
She also speculated that the sweetness of diet sodas might affect taste receptors to trigger the release of insulin when we don’t need it, or fail to release it when we do.
Another possible explanation: Research from the Johns Hopkins Bloomberg School of Public Health published in 2014 showed that overweight and obese people who drink diet sodas unwittingly make up for the “no-cal” nature of these beverages by ingesting more calories from food than their peers who consume sugar-sweetened drinks. The researchers noted that since diet sodas are calorie-free they don’t give the same “reward” as sugary drinks, a difference that disrupts appetite control. Essentially, when the brain gets a message that sweet calories are coming and they don’t arrive, the void can set you up for cravings that ultimately lead to consuming more calories.
I have long advised people to stay away from diet sodas. They have never been proven to promote weight loss, and the findings from the latest study add to accumulating evidence that they don’t help people lose weight. Worse, the results link these beverages with abdominal obesity and the serious health risks it presents.
Andrew Weil, M.D.