Capsaicin, a chemical found in chilli peppers, may boost your metabolism by slightly increasing the rate at which your body burns calories.

In fact, a review of 20 research studies notes that capsaicin — from supplements or the peppers themselves — may help your body burn around 50 extra calories per day (7).

Some studies report similar benefits with doses as low as 9–10 mg per day. This is equivalent to one jalapeño pepper (8Trusted Source, 9Trusted Source, 10Trusted Source, 11Trusted Source).

Moreover, capsaicin may have appetite-reducing properties.

According to a review of studies on nearly 200 people, consuming at least 2 mg of capsaicin directly before each meal appears to reduce calorie consumption, especially from carbs (12Trusted Source).

Similarly, adding cayenne pepper to your meal may increase the amount of fat your body burns for energy, especially following a high-fat meal. However, this fat-burning effect may only apply to people unaccustomed to consuming spicy foods (13Trusted Source).

That said, findings are mixed on capsaicin’s metabolism-boosting abilities (14Trusted Source).

The caffeine found in coffee may help increase metabolic rate.

Several studies have noted that people who consume at least 270 mg of caffeine daily, or the equivalent of about 3 cups of coffee, burn up to an extra 100 calories per day (15Trusted Source).

Furthermore, caffeine may help your body burn fat for energy, and it seems especially effective at boosting your workout performance (16Trusted Source).

However, its effects vary from person to person, based on individual characteristics such as body weight and age (17Trusted Source).