Am I allowed to drink protein powder mixed with water before davening Shacharis (but after Birchos Haschachar)?
Water is permissible to drink before davening. Many are lenient with tea and coffee as well. This is due to the fact that it is only a drink and many feel it necessary to be able to daven properly. A protein drink however is intended to be filling and satiating, a replacement for food more than drink. As such it should not be consumed before davening. One who is very weak or ill, whom halacha dictates may even eat before davening, would be permitted in this drink as well.