It's counterintuitive, but zero-calorie artificial sweeteners might cause weight gain as well as other health issues, according to an opinion piece published July 10 in the journal Trends in Endocrinology and Metabolism.
The fake sugars disturb the body's ability to accurately count calories and, as a result, diet foods and drinks could actually end up encouraging weight gain, according to Susan Swithers, a professor of behavioral neuroscience at Purdue University in West Lafayette, Ind., who summed up recent research on artificial sweeteners.
Chemical sweeteners — such as sucralose, aspartame and saccharin — may also increase the risk of health problems like heart disease and diabetes, some evidence suggests, she says.
Swithers (not to be confused with him) said studies of people who regularly consume diet soft drinks over time have found that those people are at higher risk for weight gain and obesity than people who don't drink sodas at all, according to U.S. News and World Report.
Diet soda drinkers also appear to have elevated risks for type 2 diabetes, heart disease and metabolic syndrome. The risks for these health effects seem to be similar in people who drink diet sodas and those who drink regular sodas.
The problem is that the taste of something sweet preps the brain and the gut for digestion of incoming calories. When the calories don't show, as happens with artificial sweeteners, normal metabolic responses misfire. Insulin doesn't increase; hormones that increase the feeling of fullness and satisfaction aren't triggered; and the brain doesn't get a feeling of reward from the dopamine that sugars release.
As a result of repeated exposure to fake sugar, when real sugar and real calories come along, the body doesn't respond to them as strongly as it should. Calories don't end up making you feel as full as they should, so you don't get the signals that might stop you from overeating. “The downside to drinking the diet sodas is that they may undermine these unconscious processes that could help us regulate our weight and other things like blood sugar,” Swithers said.
Artificial sweeteners may also trick us into thinking we can eat more calories than we really should. It's the ol' “I can eat this cheeseburger because I'm having a Diet Coke” line of thinking.
“I think there are multiple things that are contributing to this,” Swithers said. “Psychology is a factor, but physiology can also be altered.”
Like they always say, you can't fool Mother Nature.
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