There are numerous causes of a constant fullness in the stomach, but the primary cause is a condition called early satiety. The main symptom of early satiety is the feeling of being full earlier than normal and consuming less food because of it, according to MedlinePlus. Other causes of constant stomach fullness include gas, constipation, pregnancy and swallowed air.
Numerous health conditions can cause early satiety, including peptic ulcers, tumors, gastroesophageal reflux disease, a problem with the nervous system and an obstruction. If the constant fullness lasts for several days or weeks and does not go away, a proper medical examination is needed to determine the exact cause of the problem. If a doctor suspects early satiety as the cause of the patient's stomach fullness, they will likely perform a series of tests including a complete blood count, stool testing, X-rays and an upper endoscopy.
If the patient has early satiety, the doctor may advise strict adherence to a liquid diet. It can also be beneficial to consume smaller and more frequent meals rather than trying to consume normal-sized meals. Eating a high-fat diet can cause early satiety to worsen, so patients are recommended to watch what they eat and try to consume less fat. Keeping a diet log may also be a helpful tool for patients to give to their doctor.