A cup of coffee may wake you up and get you going in the morning and the caffeine in your coffee might also help you burn calories. According to MayoClinic.com, caffeine may stimulate thermogenesis, which is one way your body generates heat and energy. Because the thermogenic effect generates heat, thermogenesis burns calories, according to Elisa Zied, a registered dietitian in New York City and author of "Nutrition at Your Fingertips."
The word "thermogenesis" means the production of heat, according to Zied, while caffeine is a bitter substance found in certain plants, notes Medline Plus, a service of the National Institutes of Health. It can also be man-made and added to certain foods. Caffeine is found in coffee, tea, chocolate, caffeinated colas and some over-the-counter medicines, including diet pills. In addition to having a thermogenic effect, Medline Plus reports that caffeine reduces the appetite.
A study in the "American Journal of Clinical Nutrition" noted that caffeine has a thermogenic effect. In the investigation of the effects of caffeine in healthy people who regularly consumed moderate amounts of caffeine, 100 mg, 200 mg and 400 mg of caffeine all stimulated thermogenesis. The more caffeine consumed, the higher the thermogenic effect. Another study suggests thermogenesis may be more pronounced in certain people. In a small study of caffeine-induced thermogenesis in 10 lean and 10 obese women, the thermogenic effect was greater in lean women and lasted longer, compared to obese women consuming caffeine.
Caffeine may slightly boost weight loss or prevent weight gain, confirms MayoClinic.com. In addition to calorie-burning via the thermogenic effect, caffeine increases the amount of urine the body secretes, resulting in water loss. It is still unclear whether caffeine results in significant or permanent weight loss. MayoClinic.com indicates research on the connection between caffeine and weight loss isn't yet definitive. In fact, some studies have found decaffeinated coffee may spur modest weight loss, which suggests substances or factors besides caffeine may play a role in the weight loss.
Caffeine is safe for most people when consumed in moderation. Consuming more than four cups of caffeinated coffee per day, however, may keep you from getting enough healthful sleep, trigger headaches, and even cause abnormal heart rhythms, reports Medline Plus. Plus, caffeine may interact with certain antibiotics and asthma medications. Also keep in mind some specialty coffee drinks are high in calories and fat, as well as caffeine. Drinking too many of these fatty caffeinated drinks could result in weight gain, not loss.