Celsius is a canned fitness energy drink built around a blend of caffeine, green tea extract, guarana, ginger root, taurine, and B vitamins, marketed as a thermogenic beverage that helps burn calories and boost metabolism. Unlike traditional energy drinks that lean heavily on sugar and synthetic caffeine alone, Celsius positions itself as a cleaner option for gym-goers and active people, with zero sugar and no artificial colors in most of its product lines. The thermogenic angle sets it apart from the pack, but how much of that claim holds up depends on which ingredient you examine and what you expect it to do.
What Is Actually in the Can
A standard 12-ounce can of Celsius contains 200 milligrams of caffeine, sourced from a combination of green tea extract, guarana seed extract, and green coffee bean extract rather than a single synthetic caffeine source. The rest of the formula includes ginger root extract, taurine, and a suite of B vitamins (B2, B3, B5, B6, B7, and B12) along with the trace mineral chromium. Most Celsius varieties contain no sugar, using sucralose or stevia as sweeteners depending on the product line (the “Stevia” line uses only stevia, while the original line uses sucralose). The brand wraps several of these ingredients into a proprietary blend it calls MetaPlus, which makes it difficult to know the exact dose of each botanical, though the total caffeine content is disclosed.
The ingredient list reads like a who’s who of compounds that have each been studied individually for metabolic or performance effects. The question worth asking is whether those ingredients, at the doses present in a single can, produce meaningful results when combined in a fizzy drink and consumed before a workout or at your desk.
Three Sources of Caffeine and Why That Matters Less Than You Think
Celsius draws its caffeine from green coffee bean extract, guarana seed extract, and green tea leaf extract. The marketing implies that plant-sourced caffeine is somehow different from the synthetic variety found in most energy drinks, but the pharmacology does not support a meaningful distinction. A crossover trial comparing green coffee bean extract to synthetic caffeine found that the two delivered virtually identical blood levels at the same speed, with peak concentrations and total absorption that were statistically indistinguishable.1PubMed Central. A Prospective Randomized, Double-Blind, Two-Period Crossover Pharmacokinetic Trial Comparing Green Coffee Bean Extract—A Botanically Sourced Caffeine—With a Synthetic USP Control Guarana tells a similar story: when tested against an equivalent amount of free caffeine, the rate of release and the rate of absorption across the gut were the same at both acidic and near-neutral pH levels.2Journal of Pharmacy and Pharmacology. Dissolution and absorption of caffeine from guarana
In practical terms, your body does not care whether caffeine arrives wrapped in a coffee bean, a guarana seed, or a tea leaf. It is the same molecule, absorbed the same way, producing the same stimulant effects. The multi-source caffeine approach in Celsius is a branding choice, not a pharmacological one. What does matter is the total dose: 200 milligrams is roughly equivalent to two standard cups of brewed coffee, which is moderate for most healthy adults but enough to cause jitters, rapid heartbeat, or anxiety in people who are caffeine-sensitive or consuming other caffeinated products the same day.
Green Tea Extract and the Thermogenic Pitch
The core of the Celsius marketing story rests on thermogenesis, the idea that the drink raises your metabolic rate and shifts your body toward burning more fat. Green tea extract, specifically its catechin compounds like EGCG, is the primary ingredient behind this claim. The proposed mechanism involves catechins slowing the breakdown of norepinephrine in the nervous system while caffeine independently extends the activity of a signaling molecule inside cells, and the combination produces a longer and stronger stimulation of calorie-burning pathways.3The American Journal of Clinical Nutrition. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans
Individual studies have produced genuine results. One trial in healthy people found that green tea extract ingestion increased whole-body fat oxidation by about 17% compared to a placebo.4The American Journal of Clinical Nutrition. Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans Another study reported a 24% increase in fat oxidation at rest and a 29% increase during the recovery period after exercise when participants consumed green tea extract beforehand.5PubMed Central. Green Tea, Intermittent Sprinting Exercise, and Fat Oxidation Those percentages sound impressive, but they describe relative increases in a physiological process that burns a fairly small number of calories per minute. The absolute difference between burning fat at 0.045 grams per minute versus 0.059 grams per minute is real but modest in the context of a full day’s energy balance.
When you zoom out and look at the full body of research on green tea extract and fat metabolism, the picture gets murkier. A review that pulled together findings from both short-term and longer-term studies concluded that while a number of studies have observed positive effects on fat metabolism at rest and during exercise, the overall literature is inconclusive.6PubMed Central. The effect of green tea extract on fat oxidation at rest and during exercise: evidence of efficacy and proposed mechanisms Some of the variability likely comes from differences in catechin dose, caffeine dose, study population, and habitual caffeine intake of participants. If you already drink several cups of green tea or coffee daily, the added effect of what is in a Celsius can may be blunted considerably.
Ginger Root Extract
Ginger is another ingredient Celsius highlights, and it has its own small thermogenic literature. A pilot study in overweight men found that consuming ginger alongside a meal increased the thermic effect of food by about 43 kilocalories per day compared to the control condition. The same study also found that participants felt significantly less hungry and less inclined to eat after the ginger meal.7PubMed Central. Ginger consumption enhances the thermic effect of food and promotes feelings of satiety without affecting metabolic and hormonal parameters in overweight men: A pilot study That calorie number, 43 per day, is quite small (less than the energy in a single cracker), but the appetite-suppression finding was more robust and may be the more relevant benefit for people trying to manage their eating habits.
However, not every study agrees. A randomized trial in healthy-weight women found that ginger intake did not increase the thermic effect of a standardized breakfast compared to placebo, and no differences emerged in oxygen consumption, heart rate, blood pressure, or metabolic markers.8Clinical Nutrition ESPEN. Acute effects of dry extract of ginger on energy expenditure in eutrophic women: A randomized clinical trial The inconsistency between these findings suggests that ginger’s metabolic effects, if they exist, are small enough to appear or disappear depending on the population studied and the dose used. In a drink where ginger is one component of a proprietary blend with an undisclosed dose, expecting a reliable thermogenic effect from it is optimistic.
The Vitamin and Mineral Load
Celsius cans are loaded with B vitamins, often at several hundred percent of the daily recommended value. The brand includes vitamins B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6, B7 (biotin), and B12. These vitamins are involved in energy metabolism at the cellular level, but supplementing beyond what your body needs does not give you extra energy. If you eat a reasonably varied diet, you are almost certainly not deficient in any of these, and the excess is excreted in your urine. The bright yellow color you may notice after drinking heavily B-fortified beverages is riboflavin leaving your body because it has nowhere useful to go.
Research on adolescents consuming fortified beverages with high B vitamin levels found that these drinks are not metabolically inert. The excess vitamin load led to greater insulin secretion, altered gut hormone release, and shifts in one-carbon metabolism, a biochemical process linked to how the body handles amino acids and certain nutrients. These effects were short-lived but measurable, and they became more pronounced with repeated consumption.9PLOS ONE. Metabolic consequences of discretionary fortified beverage consumption containing excessive vitamin B levels in adolescents This does not mean a single Celsius can is dangerous, but it challenges the assumption that megadoses of B vitamins in a drink are harmless window dressing.
Celsius also contains chromium, typically as chromium picolinate. A study on a drink containing amino acids and chromium picolinate found that the combination lowered the post-meal glucose spike by nearly 30% and appeared to improve insulin efficiency.10Functional Foods in Health and Disease. A drink containing amino acids and chromium picolinate improves postprandial glycemia at breakfast in healthy, overweight subjects Whether this translates to a meaningful health benefit from the chromium dose in a Celsius can, consumed in a different context and alongside different ingredients, is unclear. Chromium supplementation research has been a mixed bag for decades.
Studies Done Specifically on Celsius
A handful of published studies have tested the Celsius drink itself rather than its individual ingredients in isolation. In a pilot study comparing Celsius to Diet Coke, the Celsius trial produced significant increases in metabolic rate at every time point measured: roughly 14% at one hour, 14% at two hours, and about 9% at three hours after drinking it. The Diet Coke trial showed only small, non-significant metabolic bumps of around 4 to 6%.11PubMed Central. Metabolic responses to the acute ingestion of two commercially available carbonated beverages: A pilot study The implication is that the combination of caffeine and botanical extracts in Celsius does produce a metabolic effect beyond what caffeine alone delivers in a typical diet soda.
A separate study on a commercial thermogenic drink (matching the ingredient profile of Celsius) confirmed that resting energy expenditure increased significantly at 60, 120, and 180 minutes after consumption, and free fatty acid concentrations in the blood rose at every measured time point, suggesting the body was mobilizing stored fat for energy.12PubMed Central. Acute effects of ingesting a commercial thermogenic drink on changes in energy expenditure and markers of lipolysis These are real physiological changes, but “mobilizing fat” and “losing meaningful weight” are different things. More fat floating in your bloodstream does not guarantee that you will burn it off; it just means the body has released it from storage. If you are not actively exercising or running a calorie deficit, much of it can simply get re-stored.
When researchers looked at whether these metabolic shifts differed between men and women, they found that men had higher absolute resting energy expenditure at all time points, while women who drank the thermogenic beverage actually showed higher free fatty acid concentrations. Men in the thermogenic group lost significantly more body fat over 28 days compared to women in the placebo group.13The Journal of Strength & Conditioning Research. Effect of Gender on the Metabolic Impact of a Commercially Available Thermogenic Drink This is a small study, and comparing the male treatment group to the female placebo group rather than same-sex comparisons limits what you can conclude from it. But it does suggest that individual responses to this type of drink vary considerably.
Research looking at Celsius and exercise performance found that while the drink appeared to modify neuromuscular timing in leg muscles, the changes in performance measures like single-leg heel raises were not statistically significant.14Journal of Sports Research. The influence of energy drinks on lower limb muscle fatigue and recovery in healthy young adults Any performance boost you feel from Celsius is most likely attributable to its caffeine content, which has well-established ergogenic properties across many types of exercise, rather than something unique about its botanical blend.
Cardiovascular and Safety Considerations
Celsius carries the same safety profile concerns as any energy drink delivering 200 milligrams of caffeine in a single serving. A systematic review of energy drinks and cardiovascular health found that about 61% of included studies showed a statistically significant increase in heart rate, roughly 54% showed an increase in systolic blood pressure, and about 62% showed an increase in diastolic blood pressure.15PubMed Central. The Effects of Energy Drinks on the Cardiovascular System: A Systematic Review These changes are typically modest in healthy adults and tend to resolve within a few hours, but they can matter for people with underlying heart conditions or hypertension.
A comprehensive review of energy drink effects on the body found a significant prevalence of adverse effects, particularly on the cardiovascular and nervous systems, with concerns around excessive or chronic consumption.16PubMed Central. The Dark Side of Energy Drinks: A Comprehensive Review of Their Impact on the Human Body Most of the serious case reports, such as seizures and metabolic emergencies, involve people who consumed multiple cans in rapid succession or combined energy drinks with other stimulants.17PubMed Central. Caffeinated energy drink intoxication A single can of Celsius at 200 milligrams of caffeine is within the range most healthy adults tolerate without problems, but stacking it with coffee, pre-workout supplements, or other energy drinks during the same day can push total caffeine intake into territory where adverse effects become likely.
One small study in young males found that acute energy drink consumption did not significantly alter cardiovascular or autonomic function during moderate-intensity exercise, suggesting that for young, healthy people exercising at moderate effort, a single serving is unlikely to cause immediate cardiac trouble.18The Aquila Digital Community. Investigating the Cardiovascular and Autonomic Responses to Energy Drink Consumption: The Role of Energy and Calorie Content The risk profile shifts for older adults, people with heart conditions, pregnant women, and adolescents, all of whom are typically advised to limit or avoid high-caffeine beverages.
Caffeine Interactions Worth Knowing About
If you take prescription or over-the-counter medications, the caffeine in Celsius is worth a closer look. Caffeine is processed by a liver enzyme called CYP1A2, which also handles a number of common drugs. When a medication competes with caffeine for that same enzyme, caffeine can build up in the body to unexpectedly high levels, or the medication’s breakdown can slow down, changing its effectiveness or side-effect profile.19PubMed. Clinically significant pharmacokinetic interactions between dietary caffeine and medications Certain antibiotics (like ciprofloxacin), some antidepressants, the asthma drug theophylline, and oral contraceptives are all known to interact with caffeine through this pathway. People taking these medications sometimes notice that caffeine “hits harder” or lasts longer than usual, which is exactly what is happening biochemically.
Tolerance to caffeine’s effects is real and develops relatively quickly with daily use, but that tolerance can be overwhelmed when caffeine metabolism becomes saturated, either from high intake or from a drug interaction slowing its clearance. If you are a daily Celsius drinker who starts a new medication, it is worth flagging the caffeine habit with your prescriber, especially if you notice new symptoms like insomnia, heart pounding, or increased anxiety that you did not have before.
Who Celsius Is Really For
Celsius markets aggressively to fitness-minded consumers, particularly younger adults. Estimates of energy drink use across adolescent to middle-aged populations have ranged from about 24% to 56%, and the ingredients most commonly featured in these products, including caffeine, taurine, guarana, ginseng, and B vitamins, overlap heavily with the Celsius formula. Research has generally attributed the ergogenic benefits seen with energy drinks to their caffeine and glucose content rather than to the botanical extras.20PubMed Central. Effects of commercial energy drink consumption on athletic performance and body composition Since Celsius contains no sugar and relies on sweeteners instead, its performance benefits are driven almost entirely by caffeine.
This is probably the most honest way to think about Celsius: it is a well-flavored, zero-sugar caffeine delivery system wrapped in botanical ingredients that have small, real, but frequently overstated metabolic effects. The green tea extract and ginger contribute something, but that something is modest and inconsistent across different bodies and different study conditions. If you enjoy the taste and want a convenient pre-workout stimulant without the sugar load of traditional energy drinks, Celsius fills that role. If you are hoping it will meaningfully accelerate fat loss on its own, the research suggests you would be better served by focusing on exercise and overall calorie intake. The drink gives you a nudge, not a push.