Obesity: Does eating chili peppers increase or decrease risk?

This study analyzed data from 6,138 American adults aged 20 and older from the National Health and Nutrition Examination Survey (NHANES) years 2003 to 2006.

The researchers excluded pregnant individuals and those with missing or unreliable data regarding chili pepper consumption, BMI, and total calorie intake.

The participants self-reported demographic and lifestyle factors such as age, sex, education, family income, smoking status, alcohol use, physical activity, and health conditions like diabetes and hypertension.

Approximately 51% of the participants were female, and over 34% had obesity based on their BMI status.

Using a food-frequency questionnaire, the NHANES surveys evaluated chili consumption frequency over the previous 12 months.

Based on their responses, researchers divided participants into 3 groups:

• no chili intake: zero times per month (17%)
• occasional chili intake: less than once a week (74%)
• frequent chili intake: at least once a week (9%)

NHANES also estimated participant’s habitual nutrient intake by collecting dietary data over at least 2 non-consecutive days and calculating their average total calories, proteins, carbohydrates, fats, sugars, and fibers.

After collecting data from the surveys, the researchers conducted a series of statistical analyses following the Centers for Disease Control (CDC) guidelines. Their goal was to investigate the relationship between chili pepper consumption and obesity prevalence among the general adult population in the United States.

The study identified significant differences in demographic and lifestyle factors, as well as obesity risk, among the three chili pepper consumption groups.

Researchers observed variations in age, sex, ethnicity, education, marital status, income, alcohol intake, physical activity, diabetes status, and dietary habits, while smoking and hypertension rates were similar.

Although the average BMI was also similar across groups (around 28.3 to 29.0), a higher frequency of chili consumption was linked to a greater risk of obesity.

About 30% of people who rarely ate chili peppers had obesity, compared to roughly 35% of occasional chili eaters and nearly 38% of frequent chili consumers.

Further analysis indicated that, on average, frequent chili eaters had BMIs 0.71 units higher than non-eaters.

The researchers’ fully adjusted analysis also showed that the group with the highest chili consumption had a 55% greater risk of obesity than non-consumers.

Of all demographic and lifestyle factors, only gender notably impacted how chili consumption affected BMI. Additionally, the effects of chili consumption on obesity risk were more pronounced among women and individuals aged 60 and above.

However, this was an observational study, so the researchers did not establish a causal link between chili consumption frequency and obesity risk.

Capsaicin, present in chili peppers, has been widely studied for its potential anti-obesity effects.

Many studies suggest it aids in weight reduction, conflicting with the results of the present study and several other large-scale observational studies linking higher chili consumption to increased obesity risk.

Medical News Today spoke with Thomas M. Holland, MD, MS, a physician-scientist at the RUSH Institute for Healthy Aging and instructor in the Department of Internal Medicine, Division of Digestive Diseases and Nutrition at Rush University, who was not involved in the study. He provided insight into how chili peppers and other spicy foods might impact the risk of obesity.

He noted that chili peppers, as a standalone food, are highly nutritious, containing flavonoids and carotenoids, vitamins C, A, B6, and iron.

Holland further explained:

“The nutrients, flavonoids, and other compounds like capsaicin found in chili peppers can aid in weight reduction. Capsaicin can increase lipid oxidation, improve brown fat activation (leading to more energy being burned), enhance satiety, and improve gut microbiota diversity.”

Kiran Campbell, a registered dietitian nutritionist and medical nutrition advisor at Dietitian Insights, who was also not involved in the study, told MNT that chili peppers have anti-inflammatory and antioxidant properties, potentially aiding in preventing obesity-related inflammation.

“Since obesity and chronic low-grade inflammation may be linked, this suggests that the addition of chili peppers into a healthy diet may help improve or aid in preventing obesity,” she said.

According to Holland, both direct and indirect factors affected the results of the present study, with indirect factors having a greater impact.

“Specifically,” he said, “chili peppers are often consumed with high-fat, high-calorie foods, meaning that more frequent chili pepper consumption is tied to more frequent high-calorie food consumption.”

He, put simply, that this leads to weight gain if more calories are consumed than burned.

Holland also highlighted that the study ignored diet quality despite available data and used a single question about chili pepper intake—without considering type, spiciness, or serving size—making the results hard to interpret.

These limitations represent a confounding bias, which “if not properly controlled, can obscure the true relationship between the variables being studied.”

“The quality of the diet, or the foods that chili peppers are consumed with, will significantly impact the outcome,” he affirmed.

The study authors suggest that “controlling chili intake frequency could potentially contribute to improved weight management in the general population.”

Holland cautioned, “It is appropriate to study individual foods, food groups, and nutrients. However, it is crucial to have all the necessary information to draw accurate conclusions.”

Rather than avoiding chili peppers, experts recommend consuming chili peppers alone or within healthier recipes instead of the calorie-dense or high-fat dishes in which chili is most often used.

“There is no need to eliminate chili peppers from your diet in the fear of gaining weight. Instead, look more at HOW you are using chili peppers. Alone, chili peppers are a great low-calorie vegetable that can add flavor and spice to foods and may aid in weight loss if used in conjunction with a healthy diet and exercise plan.”
— Kiran Campbell, RDN

Holland agreed, stating, “The ultimate implication here is to be mindful of what you consume with your foods.”

“Both what we consume and how it is prepared are equally important,” he concluded.

Campbell urged more long-term human studies, considering multiple confounders and examining specific categories and culinary uses of chili pepper.