What Are Symptoms of Low Protein Levels in the Blood?

Some symptoms of protein deficiency include constant cravings for carbohydrates, sweets, caffeine, chips and other processed, high-sugar or refined foods; muscle or joint pain, which is caused by a lack of protein reserves in the synovial fluid in the joints; lack of sleep, which is caused by the highs and lows in energy due to the craving for sugary foods; and moodiness and stress, which is also caused by those highs and lows in energy, according to LifeSpa. A total serum protein test can be performed to judge whether or not a patient is suffering from a protein deficiency.