MedGuidance states that stomach twitching, more commonly known as abdominal muscle spasms, are often caused by overworked muscles, dehydration, kidney stones, hypothyroidism or black widow spider bites. Rare causes include bowel obstruction, cholecystitis, hernia, intussusception and diverticulitis.
MedGuidance also explains that new exercises or frequent strenuous activities cause the abdominal muscles to spasm; this occurs due to overuse of the muscle, which results in its energy loss. The muscle then contracts suddenly, producing muscle spasms. According to MedGuidance, twitching in the stomach also happens when the muscles do not have enough water and electrolytes. Proteins in the muscles need a sufficient amount of water, glucose, potassium and other elements to function properly. The presence of kidney stones, which refer to a mass of hard crystalline mineral material in the kidneys or urinary tract, also causes intense pain in the abdomen. Furthermore, MedGuidance explains that muscle spasms are a symptom of hypothyroidism, which is an underactive thyroid that does not produce adequate hormones. MedGuidance also includes bites from black widow spiders as potential causes of stomach twitching, as a bite from the poisonous spider causes severe abdominal muscle spasms or cramps.
Better Medicine elaborates on the reasons that abdominal muscles tend to have spasms by including muscle strain during heavy use or overuse, alcohol use, drug use and fatigue. Serious causes include abdominal aortic aneurysm, aortic dissection, intestinal ischemia and perforated bowels.