Ten to 25% of healthy persons have bloating at some time or other. It is very common in those with the irritable bowel syndrome, constipation, or anorexia nervosa. Although the cause of functional bloating remains unknown, old explanations such as a low diaphragm, exaggerated lumbar lordosis, and psychiatric problems have been disproved. New suggestions on its etiology include recent weight gain, weak abdominal muscles, and retained fluid in loops of small intestine. No treatment is of proven benefit, but treatment by weight loss, exercise, and prokinetics should be studied.