This condition can be diagnosed by breath tests. Usually, people recognize a relationship between eating milk or cream and their symptoms and curtail the ingestion of these foodstuffs. If you need milk, you could consider using Lactaid, an enzyme added to milk that breaks down the sugars before you ingest them. More serious is fat malabsorption. This condition can be suspected when an individual has large volume stool and weight loss.
Fat absorption is a very complex process.
It can be suspected by the detection of fat globules in the stool during microscopic examination. For better quantification, fat content can be measured during a 72 hour stool collection. If you have fat malabsorption you will require evaluation of your pancreas, bile ducts and small intestine. ERCP is an endoscopic test. You swallow a telescope which is positioned at the opening of the bile duct.