If you are a little thin, you can eat muscle powder first. Muscle-building powder has a large carbohydrate content, which is beneficial to weight gain. Eat protein powder after gaining weight. Protein powder is mainly used to gain muscle. As for which brand to choose, I suggest choosing a foreign brand, such as Optmund or Muscle Technology. It's best to buy it in a regular place, such as pqfitness, because there are more fakes in other places.