Why so many people feel hungrier AFTER eating a protein bar

They've been billed as a meal-on-the-go and some even carry claims such as 'proven to help reduce appetite!'

But lots of Americans say they feel hungrier after they eat a protein bar.

There are Reddit forums and social media videos about the issue, where users say they were left with 'extra hunger' or ended up binging up to 20 in one sitting. 

Many gym lovers and nutritionists will advise clients to eat protein bars because protein is the more satiating than the other two macronutrients - fats and carbs.

But registered dietitians believe the culprit is sucralose, a sweetener used in the most popular protein bars from Quest, Barebells, and Fulfill.

Many fans of Quest bars and other protein bars have said they left them feeling hungrier than before, which dietitians attribute to sucralose 

Katie Lopez, a registered dietitian in New Hampshire, told DailyMail.com:  'Personally, I do not eat sucralose and minimize food additives and packaged and processed foods. 

She added that it 'triggers binges.'

She recommended bars with at least 10g of protein and whole food ingredients, such as Aloha and Rx bars, which do not use sucralose.

Consuming something sweetened artificially may lead to seeking more food, even if the sweetened item contains a high amount of protein.

The lack of calories in sucralose along with the extreme sweetness ‘further fuels the food seeking behavior,’ and the absence of a sense of reward in the brain may leave a person feeling as though they need to eat more. 

It explains the dozens of fitness forums where people have sought answers about their turbo-charged appetites after eating a Quest protein bar. 

One Reddit user said: 'After introducing and loving a Quest Bar a day or so a couple weeks ago, I definitely feel like I'm having a harder time staying under my calorie limit because I'm hungry more throughout the day.' 

Another said: 'Quest bars make me hungry... I suspect they are increasing my glucose level. I get a headache after eating one.' 

Despite its popularity and promise to beat hunger on the go, protein bars with sucralose can actually increase cravings for sweet foods.

Yale researchers said: ‘Repeated exposure trains flavor preference. A strong correlation exists between a person’s customary intake of a flavor and their preferred intensity for that flavor.’

Calorie-free sweeteners are exceedingly popular for their cost-effectiveness—a minute amount trumps real sugar in terms of sweetness—and their reported benefits over eating the real stuff.

Sucralose, marketed as Splenda, is about 600 times as sweet as real sugar. Rather than satisfy people's sweet tooth, it has been shown in studies to make people want to eat more

Many popular brands of protein bars, such as Quest, Barebells, and Fulfill use sucralose in their bars

However, evidence to back up health claims that tout the pros of artificial sweeteners is mixed. Several studies have shown that animals given a sucralose-heavy diet eat more food later despite taking in enough calories to be full.

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Matthew Kadey, a registered dietitian based in Ontario, said: ‘For females and those with obesity, drinking artificially sweetened drinks may trick the brain into feeling hungry—the brain may sense that the body did not get the sugar calories it expected from the sweet drink.

‘This, in turn, may result in people consuming more—not fewer—calories throughout the day.’

Sucralose, sold under the brand Splenda, is about 600 times sweeter than table sugar without the calories. In use since 1999, sucralose has been a go-to for people seeking to reduce their sugar intake.

Sucralose can be found everywhere, from baked goods to drinks to chewing gum. 

People intuitively reach for calorie-free sweeteners when trying to lose weight. But several large-scale studies have shown a positive relationship between eating artificial sweeteners and weight gain.

A growing body of research shows that artificial sweeteners like sucralose do not activate the food reward pathway in the brain because they do not provide calories like sugar does.

Sucralose contains no calories. The lack of calorie-to-sweetness match tricks the body into eating more sweet foods 

Eating artificial sweeteners is generally a safer bet for diabetics than real sugar, but studies into sucralose have shown that it can increase blood sugar levels, leading to a spike and subsequent crash

Artificial sweeteners do not activate what scientists call the post-ingestive component—processes such as digestion, nutrient absorption, and the release of fullness hormones.

Counterintuitively, eating too much artificial sweetener can lead to weight gain.

A 2021 report in JAMA Network Open put sucralose to the test. Researchers at the University of Southern California enrolled 74 study subjects who drank 300 milliliters of a drink sweetened with sucrose (table sugar), a drink sweetened with sucralose or water as a control over three visits.

Two hours after drinking, researchers conducted MRIs to look specifically at how areas of the subjects’ brains involved in appetite control responded to pictures of high-calorie foods like a burger and donuts.

They also measured blood sugar and, insulin levels, and other metabolic hormones in the blood. Then, they tracked the amount of food consumed at a snack buffet provided at the end of each session.

Scans showed increased activity in parts of the brain involved in appetite and cravings in both women and obese people who drank sucralose compared to those who drank drinks sweetened with real sugar. 

The women who drank sucralose-sweetened beverages also ate more at the buffet after each session.

And despite being sugar-free and billed as safe for people with diabetes, a study published in the journal Diabetes Care showed that sucralose drastically increased blood sugar levels in obese people whose bodies were particularly sensitive to insulin changes.

Ms Lopez said: ‘You can measure the glucose response to consuming a protein bar via a [continuous glucose monitor] or finger stick. If you seed a rapid rise in a short period of time followed by a rapid decrease, this will contribute to hunger.’