Spicing up meals slows eating and cut calories, study finds

Turning up the heat on meals may prove effective in cutting back on calories, suggests a new study led by researchers at Penn State, US.

At the university’s Sensory Evaluation Center, researchers evaluated the effects of increasing “oral burn” — the spiciness from ingredients like chili pepper — on how much food people eat in a meal.

The findings suggest that ramping up the heat led participants to eat less, consuming fewer calories.

“We know from previous studies that when people slow down, they eat significantly less,” says Paige Cunningham, a postdoctoral researcher and lead author on the study who earned her doctorate in nutritional sciences at Penn State in 2023.

“We suspected that making a meal spicier might slow people down. We thought, let’s test, under controlled experimental conditions in the lab, if adding a small amount of spice, but not so much that the meal is inedible, will make people eat slower and therefore eat less.”

Putting the brakes on eating

The researchers found that slightly elevating spiciness using dried chili pepper slows down eating and reduces the amount of food and energy consumed at a meal, all without negatively affecting the dish’s palatability.

“This points to added chilies as a potential strategy for reducing the risk of energy overconsumption,” said John Hayes, Penn State professor of food science and corresponding author on the paper.

“While portion control wasn’t the explicit goal of this study, our results suggest this might work. Next time you’re looking to eat a little less, try adding a blast of chilies, as it may slow you down and help you eat less.”

The team completed three related experiments on 130 adults served one of two lunch meals — beef chili or chicken tikka masala — in one of two versions: mild or spicy. The spiciness level was controlled by carefully varying the ratio of hot versus sweet paprika added to the dishes to vary the heat while keeping the chili flavor constant.

The researchers then recorded participants on high-definition video while they ate their meals to monitor their eating behaviors. From the videos, Hayes’ team measured the amount of food and water consumed, meal duration, eating speed in grams per minute, bite rate, and bite-size, and collected ratings on appetite, liking, and spiciness before and after the meal.

“Formulating the recipes took a long time for the chicken tikka,” says Cunningham. “It took so many rounds of testing that my lab mates were sick of it. But science is about trial and error. I’d make a recipe, see how far I could push the spiciness, and we’d taste it. We did that until we reached a level where palatability was matched even when spiciness increased.”

Slow it down with spicy

The study suggests the reduction in intake is driven by changes in oral processing behaviors, she explained. Specifically, participants ate the spicier meals more slowly.

Cunningham explains that slower eating often means food is kept in the mouth longer, which can help signal fullness and lead to eating less. Other studies that slow eating rate by manipulating texture have shown similar effects, she adds.

“What’s critical here is that the reduction in intake occurred without negatively impacting how much participants liked the food,” notes Hayes.

He adds that water intake did not vary significantly between spicy and mild meals. This suggests that one seemingly obvious explanation — that people drank more water and filled up faster — was not the primary reason people ate less.

“This is why we need to do empirical studies of behavior, because what you might intuitively expect is often not the case,” he concedes.

Hayes also highlights that appetite ratings made before and after the meals were similar, suggesting participants still felt full after the spicy meal, despite eating less of it.

Looking ahead, the team is now focused on understanding how oral burn can impact other eating behaviors, like snacking.

Weight loss-aiding heat may not be the only benefit of chili pepper. One previous study linked its consumption to a reduction of risk for cardiac and cerebrovascular-related death. Chili peppers contain a large variety of phytochemicals with well-known antioxidant properties.