Protein powder can be eaten on an empty stomach. Protein powder is a nutrient, and the most important feature of a nutrient is that it is easily digested and absorbed by the gastric mucosa, and the stimulating effect on the gastric mucosa is very small, so protein powder can be eaten on an empty stomach. Patients with excessive stomach acid or a weak spleen and stomach try not to eat protein powder on an empty stomach. Patients with a weak spleen and stomach have disordered gastrointestinal function and reduced digestive function of the spleen and stomach, and eating protein powder on an empty stomach can easily stimulate the gastric mucosa to secrete large amounts of stomach acid, leading to abdominal pain and diarrhea. If diarrhea occurs when eating protein powder on an empty stomach, it is not suitable for eating on an empty stomach and can be paired with carbohydrates like bread. Also note that you can not use boiling water, protein is composed of peptides, encounter strong acid, high temperature will lose its original nutritional value, so try to use lukewarm water to brew. Also pay attention not to eat too much at once, otherwise it will increase the burden on the liver and lead to liver and kidney failure.