Why Drinking Diet Soda Makes You Crave Sugar

Recommendations on limiting sugar consumption vary around the world, with guidelines ranging from “[l]imit sweet desserts to one every other day” to “[k]eep sugar consumption to 4 or less occasions per day.” In the United States, the American Heart Association is leading the charge, “proposing dramatic reductions in the consumption of soft drinks and other sweetened products” and recommending fewer than about 5 percent of calories a day from added sugars, which may not even allow for a single can of soda.

Why is the American Heart Association so concerned about sugar? “Overconsumption of added sugars has long been associated with an increased risk of cardiovascular disease,” meaning heart disease and strokes. We used to think added sugars were just a marker for an unhealthy diet. At fast-food restaurants, for example, people may be more likely to order a cheeseburger with their super-sized soda than a salad. However, the new thinking is that the added sugars in processed foods and drinks may be independent risk factors in and of themselves. Indeed, worse than just empty calories, they may be actively disease-promoting calories, which I discuss in my video Does Diet Soda Increase Stroke Risk as Much as Regular Soda?.

At 1:14 in my video, you can see a chart of how much added sugar the American public is consuming. The data show that only about 1 percent meet the American Heart Association recommendation to keep added sugar intake down to 5 or 6 percent of daily caloric intake. Most people are up around 15 percent, which is where cardiovascular disease risk starts to take off. There is a doubling of risk at about 25 percent of calories and a quadrupling of risk for those getting one-third of their daily caloric intake from added sugar.

Two hundred years ago, we ate an estimated 7 pounds of sugar annually. Today, we may consume dozens of pounds of sugar a year. We’re hardwired to like sweet foods because we evolved surrounded by fruit, not Froot Loops, but this adaptation is “terribly misused and abused” today, “hijacked” by the food industry for our pleasure and their profits. “Why are we consuming so much sugar despite knowing too much can harm us?” Yes, it may have an addictive quality and there’s the hardwiring, but the processed food industry isn’t helping. Seventy five percent of packaged foods and beverages in the United States contain added sweeteners, mostly coming from sugar-sweetened beverages like soda, which are thought responsible for more than a 100,000 deaths worldwide and millions of years of healthy life lost. Given this, can we just switch to diet sodas? By choosing diet drinks, can’t we get that sweet taste we crave without any of the downsides? Unfortunately, studies indicate that “[r]outine consumption of diet soft drinks is linked to increases in the same risks that many seek to avoid by using artificial sweeteners—namely type 2 diabetes, metabolic syndrome heart disease, and stroke.” At 3:15 in my video, you can see data showing the increased risks of cardiovascular disease associated with regular soft drinks and also diet soda. They aren’t that dissimilar.

“In other words, the belief that artificially sweetened diet beverages reduce long-term health risks is not supported by scientific evidence, and instead, scientific data indicate that diet soft drink consumption may contribute to the very health risks people have been seeking to avoid.” But, why? It makes sense that drinking all that sugar in a regular soft drink might increase stroke risk, due to the extra inflammation and triglycerides, but why does a can of diet soda appear to increase stroke risk the same amount? It’s possible that the caramel coloring in brown sodas like colas plays a role, but another possibility is that “artificial sweeteners may increase the desire for sugar-sweetened, energy-dense beverages/foods.”

The problem with artificial sweeteners “is that a disconnect ultimately develops between the amount of sweetness the brain tastes and how much glucose [blood sugar] ends up coming to the brain.” The brain feels cheated and “figures you have to eat more and more and more sweetness in order to get any calories out of it.” So, “[a]s a consequence, at the end of the day, your brain says, ‘OK, at some point I need some glucose [blood sugar] here.’ And then you eat an entire cake, because nobody can hold out in the end.”

If people are given Sprite, Sprite Zero (a zero-calorie soda), or unsweetened, carbonated, lemon-lime water, but aren’t told which drink they’re getting or what the study is about, when they’re later offered a choice of M&M’s, spring water, or sugar-free gum, who do you think picks the M&M’s? Those who drank the artificially sweetened soda were nearly three times more likely to take the candy than those who consumed either the sugar-sweetened or unsweetened drinks. So, it wasn’t a matter of sweet versus non-sweet or calories versus no-calories. There’s something about non-caloric sweeteners that somehow tricks the brain.

The researchers did another study in which everyone was given Oreos and were then asked how satisfied the cookies made them feel. Once again, those who drank the artificially sweetened Sprite Zero reported feeling less satisfied than those who drank the regular Sprite or the sparkling water. “These results are consistent with recent [brain imaging] studies demonstrating that regular consumption of [artificial sweeteners] can alter the neural pathways responsible for the hedonic [or pleasure] response to food.”

Indeed, “[t]he only way really to prevent this problem—to break the addiction—is to go completely cold turkey and go off all sweeteners—artificial as well as fructose [table sugar and high fructose corn syrup]. Eventually, the brain resets itself and you don’t crave it as much.”

We’ve always assumed the “[c]onsumption of both sugar and artificial sweeteners may be changing our palates or taste preferences over time, increasing our desire for sweet foods. Unfortunately, the data on this [were] lacking”…until now. Twenty people agreed to cut out all added sugars and artificial sweeteners for two weeks. Afterwards, 95 percent “found that sweet foods and drinks tasted sweeter or too sweet” and “said moving forward they would use less or even no sugar.” What’s more, most stopped craving sugar within the first week—after only six days. This suggests a two-week sugar challenge, or even a one-week challenge, may “help to reset taste preferences and make consuming less or no sugar easier.” Perhaps we should be recommending it to our patients. “Eating fewer processed foods and choosing more real, whole, and plant-based foods make it easy to consume less sugar.”

Speaking of stroke, did you see my Chocolate and Stroke Risk video?

For more on added sugars, see:

You may also be interested in my videos on artificial and low-calorie sweeteners:

In health,
Michael Greger, M.D.

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