Nutrition supplements that are claimed to acutely increase fat metabolism or energy expenditure, impair fat absorption, increase weight loss, increase fat oxidation during exercise, or somehow cause long-term adaptations that promote fat metabolism.

Fat burners are a category of dietary supplement that can improve your body’s ability to burn its own fat. Many of these supplements contain several ingredients, each with its own potential mechanism of action, and they are often marketed as being able to increase fat metabolism or energy expenditure, increase fat oxidation during a workout, and cause long-term adaptations that promote fat metabolism.

Common ingredients found in fat burners include caffeine, green tea extract, conjugated linoleic acid (CLA), L-carnitine, and various plant extracts. These ingredients supposedly work by:

• Increasing energy expenditure: Some ingredients such as caffeine are stimulants that can increase the number of calories your body burns each day.
• Increasing lipolysis and fat oxidation: Some substances can boost the amount of fat your body is burning when you’re exercising.
• Decreasing fat absorption: Some compounds such as green tea extract can aid in reducing the amount of fat your body absorbs from the food you eat.

It’s important to note that while some research suggests that fat burners can be effective, they are not a replacement for a healthy diet and regular exercise. They can aid in weight loss, but the most effective way to lose weight is through sustained lifestyle changes. Moreover, fat burners can have side effects, including increased heart rate, high blood pressure, and other issues, so they should be used under the supervision of a healthcare provider.