Caffeine is already the most widely used stimulant on Earth, and in the United States alone it’s estimated that 90 percent of people consume it every single day.
So when research started suggesting that caffeine can help with fat loss, increase the metabolism, and suppress appetite, many people were quick to declare their morning cup of coffee or tea as the best thing they could put in their bodies.
To be sure, there are many, many health benefits in coffee and tea but is it really true that their caffeine content could give your diet an edge? We’ve interviewed a physician and reviewed a bunch of studies to answer the following questions:
- Does Caffeine Burn More Calories?
- Does Caffeine Burn Fat?
- Does Caffeine Suppress Appetite?
- The Downside of Caffeine
Editor’s note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. Speak with your physician before undertaking any new weight loss, supplement, or exercise regimen.
Does Caffeine Burn More Calories?
- Caffeine may increase your daily calorie burn by 50 to 200 calories
- The effect is more pronounced in leaner people
This one seems pretty certain. Consuming caffeine has been linked to an increase in the amount of calories you burn, a process called thermogenesis. You generate a greater need for calories than if you hadn’t consumed caffeine.
“According to a study in The American Journal of Physiology, the magnitude of coffee-induced thermogenesis and the influence of coffee ingestion on substrate oxidation were investigated in 10 lean and 10 obese women,” says Dr. Aastha Kalra, a New York-based physician who specialized in weight loss.(1) “The study showed that caffeine increased fat burning by as much as 7 percent in lean people, while the increase was only about 5 percent in obese individuals.”
If your resting metabolic rate has you burning 2,000 calories a day, that’s roughly a hundred calories. Other research has reached similar conclusions, with the estimated calorie burn ranging from 3 to 11 percent, or somewhere in the area of 60 to 200 calories.(2)(3)(4) These studies used doses of about 100 to 200 milligrams of caffeine; the USDA puts a small cup of coffee at 95 milligrams while a tall (355ml) coffee from Starbucks has about 235 milligrams.
Sixty to two hundred calories per day is significant, though it’s worth remembering that one tablespoon of butter of olive oil has 119 calories, so it’s still worth monitoring your calorie intake to make sure the difference is worthwhile.
[How to best combine caffeine with other fat burners? Check out our list of the best fat burner pills for women.]
Does Caffeine Burn Fat?
- Caffeine is linked to a temporary increase in fat oxidation
Here we’re talking about lipolysis, or fat oxidation. Generally speaking, the body either burns carbs (glucose) or fat (fatty acid) for energy, and caffeine may increase the amount of fat you burn.(5)(6)(7)
“Caffeine can also promote lipolysis or fat burning,” says Dr. Kaalra. “What caffeine does is stimulate the central nervous system, which sends signals to the fatty tissues telling them to break down fat. So it does so by increasing blood levels of hormone called epinephrine, which is also called adrenaline, and it travels through the blood to fatty tissues creating these signals to break down fat.”
Some studies have put the temporary increase in fat oxidation at up to 44 percent, though that’s with pretty high doses — other studies have put it closer to 10 to 30 percent, depending on your leanness.(8)(1)
Remember that your exercise, sleep, stress management, and other lifestyle habits also affect fat oxidation, and caffeine is just one piece of a larger puzzle, here.(9)(10) Caffeine also won’t help you burn fat unless you’re in a calorie deficit, so again, keep an eye on your calories if weight loss is your goal.
[Caffeine topped our list of the best natural fat burners — click through to read the rest.]
Doesn’t Caffeine Suppress Your Appetite As Well?
- Effect of caffeine on appetite suppression are disputed
Although caffeine gets a lot of hype as a powerful appetite suppressant, the evidence is actually pretty mixed. While some studies have noted a decrease in snacking among caffeine drinkers, a lot of high quality reviews have found no real effect on appetite.(11)(12)(13) Either there’s no effect or it depends on the individual.
The Downside of Caffeine
- Tolerance to the effects of caffeine can develop over time
“There’s a major caveat to the whole caffeine thing,” cautions Dr. Kalra. “People become tolerant to he effects of caffeine over time. So in the short term, caffeine can boost metabolic rate and help with fat burning but after a while people become very tolerant to it.”
As to whether or not the fat burning effects totally switch off, or if they reduce at the same time in the same way as the stimulatory effects, it’s hard to say.(14) But given the increases in adrenaline appear to slowly taper down, and the adrenaline is implicated in a lot of the fat oxidation, it’s fair to say that chronic, daily users of caffeine may not experience the same benefits as someone who doesn’t drink that much.
Caffeine certainly seems to have a small yet significant effect on fat oxidation and calorie burn, though the magnitude of the effect is less clear among people who consume it every day. To maintain or improve your sensitivity to caffeine, it’s wise to moderate your intake and avoid drinking it every day. This will maximize the fat burning effects — but above all, keep an eye on your calories if you’re dedicated to losing weight.
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2. Astrup A, et al. Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers. Am J Clin Nutr. 1990 May;51(5):759-67.
3. Dulloo AG, et al. Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers. Am J Clin Nutr. 1989 Jan;49(1):44-50.
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5. Kim, TW et al. Effect of caffeine on the metabolic responses of lipolysis and activated sweat gland density in human during physical activity. Food Sci Biotechnol. 2010;19(4):1077-1081
6. Keijzers GB, et al. Caffeine can decrease insulin sensitivity in humans. Diabetes Care. 2002 Feb;25(2):364-9.
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9. Knutson KL, et al. The metabolic consequences of sleep deprivation. Sleep Med Rev. 2007 Jun;11(3):163-78.
10. Aschbacher K, et al. Chronic stress increases vulnerability to diet-related abdominal fat, oxidative stress, and metabolic risk. Psychoneuroendocrinology. 2014 Aug;46:14-22.
11. Tremblay, A et al. Caffeine reduces spontaneous energy intake in men but not in women. Nutr Res. 1988 May:8(5):553-558
12. Gavrieli A, et al. Caffeinated coffee does not acutely affect energy intake, appetite, or inflammation but prevents serum cortisol concentrations from falling in healthy men. J Nutr. 2011 Apr 1;141(4):703-7.
13. Schubert MM, et al. Caffeine, coffee, and appetite control: a review. Int J Food Sci Nutr. 2017 Dec;68(8):901-912.
14. Ammon HP. Biochemical mechanism of caffeine tolerance. Arch Pharm (Weinheim). 1991 May;324(5):261-7.