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In a new study, diet drinks increased food cravings for certain groups of people. Jonathan Knowles/Getty Images
  • Previous research investigating the usefulness of diet drinks for people trying to lose weight has not been conclusive.
  • There are also questions regarding whether non-nutritive sweeteners are healthy.
  • A new study concludes that these sweeteners may not reduce a dieter’s calorie intake in the long run because they increase cravings.
  • The study looks specifically at the artificial sweetener sucralose.

A 12-ounce (oz) can of the most popular cola drink in the United States has 140 calories, while a 20-oz plastic bottle contains 240 calories.

For people who are interested in losing weight but enjoy cola or other high calorie, sugar-sweetened soft drinks, a diet version with close to zero calories may seem an attractive option.

However, a new study led by researchers from the Keck School of Medicine at the University of Southern California in Los Angeles suggests that drinks containing low calorie artificial sweeteners may not be as helpful for weight loss as many assume.

The study found that the non-nutritive sweetener (NNS) sucralose, which many diet drinks include as an ingredient, increases food cravings in women and people with obesity compared with drinks containing sucrose, a natural sugar.

Sucralose, also known by the brand name “Splenda,” is in many diet drinks. The Food and Drug Administration’s (FDA’s) most recently published list of approved artificial sweeteners includes sucralose, saccharin, aspartame, acesulfame potassium (Ace-K), neotame, and advantame.

Research suggests that more than 40% of U.S. adults consume NNS-sweetened diet sodas to satisfy a craving for sweetness without incurring a caloric penalty.

The study findings appear in the journal JAMA Network Open.

“There is controversy surrounding the use of artificial sweeteners because a lot of people are using them for weight loss,” says Kathleen Page, M.D., the study’s senior investigator.

“While some studies suggest they may be helpful, others show they may be contributing to weight gain, type 2 diabetes, and other metabolic disorders. Our study looked at different population groups to tease out some of the reasons behind those conflicting results.”

According to the researchers, the safety of artificial sweeteners remains unclear.

Michelle Routhenstein, a cardiology dietitian and owner of Entirely Nourished, told Medical News Today:

“We know that regularly drinking artificially sweetened drinks has been linked to a higher risk of stroke and heart attacks. This is likely due to artificially sweetened drinks’ negative impact on risk factors for heart attacks and strokes — inclusive of diabetes, high blood pressure, high cholesterol, and increased weight.”

Routhenstein was not involved in the study.

The researchers recruited 74 weight-stable, right-handed, non-smoking volunteers. They were aged 18–35 years, and 58% were female. None of the individuals had current medical diagnoses or a history of eating disorders, diabetes, or illegal drug use.

Each participant attended three experimental sessions with the researchers, having fasted overnight prior to arriving.

The cohort comprised relatively even numbers of people who were at a healthy weight, had overweight, and had obesity. This allowed the researchers to identify possible differences in the way their bodies responded to NNS.

At a session, each individual would consume 300 milliliters of an NNS-sweetened drink, a sugar-sweetened drink, or, as a control, water.

After each participant consumed their drink, researchers presented them with pictures of high calorie foods and used functional MRI (fMRI) scans to record activity in the regions of their brain associated with appetite and food cravings.

The researchers also monitored the participants’ blood sugar, insulin, and metabolic hormone levels.

Finally, at the end of each session, the researchers offered the participants a snack buffet and recorded the amount of food each individual consumed.

The scans and blood work revealed three significant effects that suggest that NNS-sweetened drinks may actually make limiting calorie intake harder.

  1. The fMRI scans revealed that among women and those with obesity, consuming NNS-sweetened drinks led to more activity in brain areas associated with appetite and cravings than drinking the sucrose-containing drink.
  2. There was a drop in the levels of metabolic hormones that signal being full after consuming NNS-sweetened drinks compared with sucrose-containing drinks.
  3. After consuming NNS-sweetened drinks, women, though not men, ate more snacks at the buffet at the end of the session.

Of the study, Routhenstein said:

“There have been previous studies that show the detrimental effects of artificial sweeteners, and this study adds more strength to the previous findings. This study was a randomized crossover trial that showed a higher neural reward response to non-nutritive sweeteners.”

“Our brain is smart and clearly cannot be fooled; when it sees that you are consuming a food or drink that has a very sweet taste without the calories to show for it, it looks for a caloric sugar-based food to compensate for it.”

Although Dr. Page notes that the study’s participants may have been hungrier than usual due to their pre-session fast, she says:

“Our study starts to provide context for the mixed results from previous studies when it comes to the neural and behavioral effects of artificial sweeteners. By studying different groups, we were able to show that females and people with obesity may be more sensitive to artificial sweeteners. For these groups, drinking artificially sweetened drinks may trick the brain into feeling hungry, which may, in turn, result in more calories being consumed.”