This sounds like a typical success story from social media or magazines! Such dramatic weight loss is often highlighted with certain drinks, but the actual effect usually comes about differently:

Lemon water or ginger tea: Often touted because of metabolism myths, in practice they primarily help by replacing high-energy drinks (like juices or sodas) and increasing the feeling of fullness before meals.

Apple cider vinegar water: Supposedly boosts fat burning and stabilizes blood sugar levels; however, the acidic taste usually just suppresses appetite.

Green tea or matcha: Contains caffeine and catechins, which can slightly stimulate calorie expenditure—but the main factor remains low-calorie fluid intake.

Protein shakes: When a nutrient-rich shake replaces a high-calorie meal, it creates a significant calorie deficit, leading to rapid weight loss.

Which “miracle drink” was it in this case—and are you looking for the scientific background or similar recipes