How did Abu Dharr—may God be pleased with him—gain weight from Zamzam water when it contains no carbohydrates, proteins, or fats, knowing that there are reliable scientific studies stating that one of the benefits of Zamzam water is that it helps in weight loss, and is this difference in the two cases in line with the Prophet's—peace and blessings be upon him—saying: "Zamzam water is for what it is drunk for"?

The validity of studies suggesting that Zamzam water can lead to weight loss cannot be definitively confirmed, and Allah knows best about them.

It has been authentically narrated in the story of Abu Dharr’s (may Allah be pleased with him) conversion to Islam that he gained weight solely from drinking Zamzam water. Its blessing was that it served as nourishing food, and this was not due to its chemical composition, but rather to Allah's blessing and honor bestowed upon him.

Obesity and thinness have multiple causes and may not be necessarily linked to the type of food consumed, for Allah’s will and decree are above all else.

The hadith "Zamzam water is for what it is drunk for" indicates that whoever drinks Zamzam water with a specific intention, such as nourishment or healing, it is hoped that they will attain what they intended. Many have experienced healing and nourishment from it.