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.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Cancer-Causing Caramel Color

Caramel coloring may be the most widely consumed food coloring in the world.  Unfortunately, its manufacture can sometimes lead to the formation of a carcinogen called methylimidazole, which was identified as a cancer-causing chemical in 2007. For the purposes of its Proposition 65 labeling law, California set a daily limit at 29 micrograms a day. So, how much cancer might caramel-colored soft drinks be causing? We didn’t know…until now… My video Which has more Caramel Coloring Carcinogens: Coke or Pepsi? explores these questions and more.

Researchers tested 110 soft drink samples off store shelves in California and around the New York metropolitan area, including Connecticut and New Jersey. None of the carcinogen was found in Sprite, which is what you’d expect since Sprite isn’t caramel-colored brown. Among sodas that are, the highest levels were found in a Goya brand soda, while the lowest levels were in Coke products, which were about 20 times less than Pepsi products. Interestingly, California Pepsi was significantly less carcinogenic than New York Pepsi. “This supports the notion that [labeling laws like] Proposition 65…can incentivize manufacturers to reduce foodborne chemical risks…” To protect consumers around the rest of the country, federal regulations could be a valuable approach to reducing excess cancer risk—but how much cancer are we talking about?

Johns Hopkins researchers calculated the cancer burden, an estimate of the number of lifetime excess cancer cases associated with the consumption of the various beverages. So, at the average U.S. soda intake, with the average levels of carcinogens found, Pepsi may be causing thousands of cancer cases, especially non-California Pepsi products, which appear to be causing 20 times more cancer than Coke. Of course, there’s no need for any of them to have any these carcinogens at all “as caramel colorings serve only a cosmetic purpose [and] could be omitted from foods and beverages…” But we don’t have to wait for government regulation or corporate social responsibility; we can exercise personal responsibility and just stop drinking soda altogether.

Cutting out soda may reduce our risk of becoming obese and getting diabetes, getting fatty liver disease, suffering hip fractures, developing rheumatoid arthritis, developing chronic kidney disease, and maybe developing gout, as well.

In children, daily soda consumption may increase the odds of asthma five-fold and increase the risk of premature puberty in girls, raising the likelihood they start getting their periods before age 11 by as much as 47 percent.

If we look at the back of people’s eyes, we can measure the caliber of the arteries in their retina, and the narrower they are, the higher the risk of high blood pressure, diabetes, and heart disease. Researchers performed these kinds of measurements on thousands of 12-year-olds and asked them about their soda drinking habits. Their findings? Children who consume soft drinks daily have significantly narrower arteries. “The message to patients can no longer remain the simplistic mantra ‘eat less, exercise more.’” It matters what you eat. “[S]pecific dietary advice should be to significantly reduce the consumption of processed food and added sugar and to eat more whole foods.”


Prop 65 is lambasted by vested interests, but, as I mentioned, it may push manufacturers to make their products less carcinogenic. Other Prop 65 videos include:

For more background on caramel coloring, see my video Is Caramel Color Carcinogenic?.

There are other soda additives that are potentially toxic, too. See my three-part series on phosphates:

Other coloring agents are less than healthy. For more on this, see Artificial Food Colors and ADHD and Seeing Red No. 3: Coloring to Dye For.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: