While there are several metabolism-boosting supplements on the market, only a few ingredients have the supporting research to back up their claims. Choose supplements that contain one or more evidence-backed ingredients, such as caffeine plus chlorogenic acid, EGCG or capsaicin. Some substances, however, that boost metabolism might only have a small to moderate effect on overall weight loss. The only way to guarantee results is to limit calories and get regular exercise. Consult your doctor before taking any metabolism-boosting supplements, as they might not be safe for everyone.
Caffeine Speeds Up Metabolism
Caffeine is an effective metabolism booster that works two ways: It has a thermogenic effect that burns more calories and it promotes the breakdown of fat. When men took 50 milligrams of caffeine, their thermogenic response temporarily increased 6 percent above their metabolic rate before taking the supplement, reported the European Journal of Clinical Nutrition. Since the study only included 12 men, these preliminary results might not hold true for everyone, but this is one example of caffeine's impact. In addition to helping you lose weight, caffeine might help you keep it off, according to an article in the November 2015 issue of the European Journal of Clinical Nutrition.
If you use caffeine-based supplements to perk up your metabolism, keep track of the total quantity you consume from all sources so you don't experience side effects such as restlessness, anxiety, difficulty sleeping and an increased heart rate. Some supplements contain 150 milligrams per dose -- others have double that amount -- so check the label on the brand you buy. Try to avoid supplements that have caffeine but don't report the amount because it's only listed as one ingredient in a proprietary blend.
For comparison, an 8-ounce cup of coffee has about 100 milligrams, and a caffeinated cola contains 45 milligrams in a 12-ounce drink, reports MedlinePlus. Most people can tolerate up to 400 milligrams of caffeine daily, but more is likely to cause adverse effects. Caffeine can increase the heart rate, so if you have a medical condition, ask your physician if it's safe for you to ingest caffeine.
Chlorogenic Acid Boosts Fat Metabolism
Some metabolism-boosting supplements contain green coffee bean extract, which consists of the active ingredient chlorogenic acid. Chlorogenic acid primarily increases fat metabolism. In lab studies, chlorogenic acid triggered fat cells to break down and release fatty acids, reported Phytotherapy Research in June 2014. While it's recognized as a fat-burner that may support moderate weight loss, more research is needed to verify its effectiveness, noted Gastroenterology Research and Practice in 2010.
If you want to make a bigger impact on metabolism, consider supplements that contain chlorogenic acid and caffeine. While it hasn't been studied in people, when lab rats consumed chlorogenic acid and caffeine, they lost more weight than rats taking either ingredient alone, reported the British Journal of Nutrition in September 2014.
After researchers reviewed seven previously published studies, they concluded that chlorogenic acid causes a moderate reduction in systolic and diastolic blood pressure, reported the Journal of Human Hypertension in February 2015. The report further noted that the studies had been funded by manufacturers of chlorogenic acid, which means that independent clinical trials are needed to verify the results. But if you take medications to manage blood pressure, talk to your doctor before using green coffee bean extract to be sure it's safe.
Supplemental Tea Flavonoids Increase Fat Metabolism
Green tea is a common ingredient in supplemental metabolism boosters. Part of its effect comes from caffeine, but it also contains natural plant-based antioxidants called catechins. One particular catechin called epigallocatechin-3-gallate, or EGCG, increases fat metabolism. Based on studies using lab mice, researchers reported that EGCG worked by regulating the genes involved in fat burning and thermogenesis, according to the Annals of Nutrition and Metabolism in 2009. Another study in the American Journal of Clinical Nutrition in 2013 noted that EGCG increased the activity of enzymes that promote fat breakdown.
To get results, you may need large doses of EGCG, because some of it breaks down during digestion and doesn't make it into cells in your body. Taking EGCG-containing supplements on an empty stomach might improve its absorption rate, according to a report in Antioxidants in May 2015.
Black tea also contains phytonutrients that may increase fat metabolism. It's made from the same leaves as green tea, so it also contains catechins. The leaves are then oxidized to produce black tea, and during that process, the catechins turn into theaflavins. Metabolism significantly increased in laboratory mice that got a dose of theaflavins from black tea, reported PLoS One in September 2015. But again, research is needed in humans to confirm whether or not drinking black tea has the same effect in people.
Capsaicin in Supplements
Capsaicin -- the ingredient in hot peppers responsible for their burning sensation -- also kicks up your metabolism. It stimulates the metabolic rate, increases heat production, promotes the breakdown of fat and may even prevent fat storage. When you're in negative energy balance -- which is when you consume fewer calories than you burn -- your body's metabolism naturally slows down, especially if you severely restrict calories. Capsaicin may be able to counteract this slow down while also promoting fat breakdown, reported PLoS One in July 2013.
- European Journal of Clinical Nutrition: The Effect of Caffeine, Green Tea and Tyrosine on Thermogenesis and Energy Intake
- European Journal of Clinical Nutrition: Caffeine Intake Is Related to Successful Weight Loss Maintenance
- MedlinePlus: Caffeine in the Diet
- Phytotherapy Research: Lipolytic Activity of Svetol, a Decaffeinated Green Coffee Bean Extract
- Gastroenterology Research and Practice: The Use of Green Coffee Extract as a Weight Loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials
- British Journal of Nutrition: Chlorogenic Acid and Caffeine in Combination Inhibit Fat Accumulation by Regulating Hepatic Lipid Metabolism-Related Enzymes in Mice
- Journal of Human Hypertension: The Effect of Chlorogenic Acid on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Clinical Trials
- Annals of Nutrition and Metabolism: Green Tea Epigallocatechin-3-Gallate Reduces Body Weight With Regulation of Multiple Gene Expression in Adipose Tissue of Diet-Induced Obese Mice
- American Journal of Clinical Nutrition: Catechin- and Caffeine-Rich Teas for Control of Body Weight in Humans
- Antioxidants: Food Inhibits the Oral Bioavailability of the Major Green Tea Antioxidant Epigallocatechin Gallate in Humans
- PLoS One: A Single Oral Administration of Theaflavins Increases Energy Expenditure and the Expression of Metabolic Genes
- Examine.com: Capsaicin
- PLoS One: Acute Effects of Capsaicin on Energy Expenditure and Fat Oxidation in Negative Energy Balance