Green tea has pretty much been the darling drink of the past decade, lauded for its role in reducing the risk of Alzheimer’s disease, diabetes and certain cancers. Plus, several studies show that the calorie-free elixir bolsters immunity, thanks to its abundance of antioxidant compounds called catechins. But beyond diverting diseases and keeping you cough-free, green tea may also promote weight loss.

While numerous recent reports have linked the beverage to dropping pounds and whittling waistlines, experts have yet to nail down exactly how green tea might help you get slim. However, mounting evidence points to its large cache of catechins. Green tea’s most plentiful catechin, epigallocatechin gallate, aka EGCG, sparks production of the hormone noradrenaline, which ramps up calorie burning—and could, in turn, trigger weight loss.

Although black, white, and oolong teas also offer EGCG, green tea boasts the most. This is because green tea leaves are simply steamed or dried during processing, while the others undergo oxidation, which depletes catechin levels.

A 2009 study published in the journal Obesity backs up the theory that the more catechins, the better, when it comes to weight loss. Researchers gave 182 moderately overweight Chinese adults twice-daily doses of green tea with catechin contents ranging from 30 mg to almost 900 mg. After 90 days, those who drank tea with the highest levels of catechins lost more abdominal fat than the other participants. Total body fat and body fat percentages also declined in the three groups that consumed more than 60 mg of catechins per day. Even though this particular study blitzed participants with far more catechins than the average cup of green tea offers (50 to 100 mg), the results lend credence to the antioxidant compounds’ weight loss–promoting potential.

Besides its high catechin count, green tea is also loaded with caffeine, which research shows similarly spurs the body to burn more calories and possibly help you drop pounds. Still, while caffeine may well play a role, research suggests catechins’ potential weight-loss contributions can’t be overlooked.

A 2009 study published in The Journal of Nutrition found that green tea may blast belly fat better than beverages with the same amount of caffeine but zero catechins. Researchers tracked 107 overweight or obese adults for 12 weeks as they did 180 minutes of moderate-intensity exercise each week and drank 500 ml per day of either a beverage containing 625 mg of green tea catechins and 39 mg of caffeine or a no-catechin placebo with the same amount of caffeine. At the trial’s end, the catechin group lost more weight and more abdominal fat than the placebo-sipping participants.

Researchers say more studies are needed to solidify exactly which component can take credit for green tea’s potential fat-whittling ways. Meanwhile, if it might help with weight loss while boosting immunity and lowering disease risk, why not drink up? But don’t grab just any jug, can or bottle of “green tea” and expect to drink away pounds. Beverage companies have capitalized on the brew’s buzz, meaning there are myriad products on store shelves to choose from. However, many pack in sugars, preservatives, and artificial colors and flavors, which combine for enough calories and unneeded junk to overshadow the weight-loss benefits otherwise gleaned from green tea.