When people say having protein shake help lose weight, they mean protein is good for muscle repairing, building, and strengthening. And muscle takes lots of energy to build and maintain, this helps you burn more calories. Therefore, you may lose fat faster. With that being said, the protein itself won’t cause fat loss, if you don’t do strength training to build your muscle, you don’t need so much protein. Otherwise, you get excess calorie intake than you need. This can cause fat gaining. Extra calories will be stored as fat in your body if you don’t use them.
When people say protein shake makes you gain weight, it is because protein help you build muscle, and muscle weigh more than fat. You weigh more if you have more muscle. So, you may see weight gaining after taking protein shake. However, just like we mentioned, you need to do weight training to build your muscle so that you can increase your weight.
If you take in enough protein from your meals, you don’t need extra protein shake supplement.