"A cup of green tea burns belly fat" — an advert repeated thousands of times. Let's measure its promise against the yardstick of meta-analyses.
The actual numbers
A meta-analysis found that green tea reduced weight by 0.65 kg, BMI by 0.26, and waist circumference by 1.11 cm — but with no significant change in body fat percentage[1]. Combined with caffeine, catechins lowered weight by about 1.38 kg and waist circumference by 1.93 cm compared with caffeine alone[1].
And most importantly: caffeine alone showed no significant effect on weight[2].
in the meta-analysis
on weight
clinical significance
How to read 0.65 kg
The researchers themselves describe the clinical significance of these reductions as modest at best[1]. Meaning: if you drank green tea daily for months, you might lose under a kilogram — while a single weekly delivery meal could erase all of it.
But coffee and tea aren't worthless
A systematic review and network meta-analysis on the effect of coffee and tea on glucose metabolism points to plausible metabolic benefits beyond weight[3]. The message isn't "don't drink them" — it's "don't rely on them as a weight-loss strategy".
And the bigger trap in our culture
Coffee itself is nearly calorie-free — but coffee here rarely arrives alone: dates, dessert, and a caramel iced latte with whipped cream that can exceed 400 kcal. The drink is innocent; the accompaniments are not (the hidden calories of the majlis).