Have you ever wondered how those diet sodas taste as sweet as the original, but don’t contain any calories?  Artificial sweeteners are laboratory-manufactured chemicals that are intensely sweet. They mimic the taste of sugar, without the calories, and since the 1980s have steadily become more common in processed foods, such as Diet Coke, and food for diabetics; hence, the misconception that artificial sweeteners are healthy.

Of the available sweeteners, aspartame, the common name of the chemical acesulfame-K, is 180-200 times sweeter than sugar. It is marketed under the brands Equal and NutraSweet. Aspartame has no bitter aftertaste, unlike other sweeteners, and perhaps for this reason, it has grown in popularity above other artificial sweeteners. But is it a harmless sugar alternative?

“Aspartame makes an appearance in a lot of products mostly labelled Sugar Free,” says Kirthika Pillai, certified diabetes educator based in Chennai. “It’s certainly a matter of concern that it is so widely used, and, as a rule, I never recommend aspartame or any other artificial sweetener. Commercials that show artificial sweeteners as an aid for weight loss are very misleading.”

Pillai says the conception is especially misleading for people with insulin issues, high blood pressure, or high cholesterol, or overweight people, all of whom are better off avoiding sweeteners of any kind.

Few other additives have captured as much popularity and misunderstanding as aspartame. Here, we attempt to separate fact from fiction.

Aspartame’s link to cancer in humans is weak and discredited.

In the late ’90s and early ’00s, a spate of studies came out linking very high levels of aspartame to various cancers in lab rats. A large-scale 2006 study by the US National Cancer Institute, however, found no such link among humans. More recently in 2013, amid continuing public concern and misinformation, a comprehensive review of the sugar substitute was conducted by the European Food Safety Authority, which found no proven link to cancer, and the EFSA once again cleared aspartame for human consumption. But aspartame has uniquely captured the attention of the scientific community and the public alike and continues to be studied.

Aspartame, while replacing sugar, often adds more fat to your diet.

Artificially sweetened foods, studies reveal, might be low in sugar, but are still very high in fats. That’s why binging on packaged ‘diet’ foods containing aspartame and other artificial sweeteners can still cause weight gain. In the 1980s, the San Antonio Heart Study tracked 3,682 adults across seven to eight years. After monitoring individuals’ intake of artificially sweetened beverages – and comparing them to individuals with similar initial factors such as gender and diet – it was found that Body Mass Index (BMI) actually increased among those who regularly consumed artificial sweeteners.

The implications of this closely connect to the growing problem of obesity. A 2010 study published in  the Yale Journal of Biology and Medicine established a link between rising obesity rates in the US and the popular and indiscriminate use of aspartame.

Nutritionists believe that, because of the very low calories found in foods that employ artificial sweeteners, people tend to overeat as a kind of compensation mechanism. A study published in Obesity supports this theory: Lab rats, when given a very low-calorie food, ate more of it than the regular calorie offering.

Aspartame is associated with some kooky side effects.

Maya Rathore*, 36,  first started taking aspartame on the advice of a friend who claimed to have lost weight after adding it to her diet. Rathore wasn’t diabetic, but she liked the idea of cutting back on sugar while still satisfying her sweet tooth. After substituting the sugar in her coffee every morning with no ill effect, she soon replaced most of the sugar in her diet with aspartame. But instead of losing weight, she started to experience intense hunger.

“I never felt satiated after meals and was craving food all the time,” Rathore remembers. “It was embarrassing and upsetting.”

Rathore also experienced bouts of dizziness and headaches so severe she had trouble working. After four months and a weight gain of four kilos, she decided to get professional help. She consulted a dietician who advised her to stop using aspartame and instead include a moderate amount simple sugars, like those in fruit, in her diet.

“In two weeks, I stopped being wracked with hunger and the headaches subsided, too,” she says. “I had more energy. It was such a relief.”

Many side effects of aspartame have been reported over the years, but none have been proven in large-scale studies. Some people, like Rathore, complain of headaches and dizziness; confusion, even disorientation and memory loss have been said to be a result.

“For those prone to migraines, aspartame could possibly act as a trigger,” says Geeta Shenoy, a practicing dietician in Mumbai. “Some people are more sensitive to aspartame, and side effects may stem from excessive intake.”

Other health conditions, such as multiple sclerosis (MS), systemic lupus (an auto immune disorder), seizures, blindness, depression, anxiety, and birth defects, have been linked to – but not proven to originate from – long-term aspartame consumption.

One risk is clear, however.

Aspartame has been found to be unsafe for people with the rare genetic disorder phenylketonuria (PKU), for whom the artificial sweetener acts as poison.

So, what’s the final word?

“While aspartame isn’t unsafe, it’s always best to be cautious,” Shenoy says.

She advises moderation. While the US Food and Drug Administration has okayed a daily consumption of 50 milligrams per kilo of body weight, Shenoy finds this extreme. She suggests a daily intake of no more than 4-5 milligrams total per day, or roughly the equivalent to five balls of the sweetener.

“I’d also advise children, dieters and those who are not diabetic to steer clear of it entirely,” Shenoy says. “One should also be wary of your intake of diet drinks or anything labelled sugar-free, which is bound to have aspartame in higher amounts.”

Pillai agrees, suggesting small quantities of natural sweeteners, such as honey or coconut palm sugar, instead.

“The best way is to eat a proper diet,” says Pillai. “Always choose fresh, whole foods and try limiting processed packaged foods, especially those with a long expiry date and labelled sugar-free.”

*Name has been changed to protect privacy.