Is it forbidden to take brewer's yeast pills for the purpose of gaining weight?

The basic principle concerning foods and drinks is that they are permissible unless there is evidence to prohibit them, as stated in the Almighty's words: "It is He who created for you all of that which is on the earth" and "O mankind, eat from what is on earth [that is] lawful and good."

"Brewer's yeast" consists of fungi extracted from living organisms, produced by fermenting starches or sugar-rich substances. It is originally beneficial and rich in vitamins, minerals, acids, and proteins.

Its name, "brewer's yeast," came about because it was historically made from the byproducts of beer fermentation. However, nowadays it is manufactured from the fungal yeast plant.

Therefore, there is no harm in consuming brewer's yeast tablets, as they are neither impure nor intoxicating, and they do not affect the mind.