What mass gainers actually contain
Primarily a large amount of carbohydrate (often from cheap sources like maltodextrin) combined with a moderate amount of protein — essentially a high-calorie shake designed to make hitting a calorie surplus easier for people who struggle to eat enough.
Who genuinely benefits from this
People with a naturally fast metabolism or small appetite who struggle to consume enough calories through regular meals to support muscle gain — for this specific group, the convenience genuinely solves a real problem.
The cost comparison worth doing
A homemade shake — milk, banana, peanut butter, oats, and a scoop of regular whey protein — often provides similar calories and better overall nutrition quality at a meaningfully lower cost than commercial mass gainer products.
The downside to be aware of
The high sugar and refined carbohydrate content in many mass gainers can contribute to excessive fat gain alongside muscle if not paired with adequate training volume — 'dirty bulking' isn't an efficient strategy even when the goal is gaining weight.