Its probably best to know what is involved in fat absorption first. Fat digestion starts with the secretion of bile acids from the liver and the secretion of a pancreatic enzyme called lipase. They are mixed in the small intestine just distal to the stomach and duodenum. Their they are mixed with chyme to break down dietary fat. The bile salts breaks down fat and turns it into smaller droplets of triglycerides. Then the lipase turns these into monoglycerides and fatty acids. The monoglycerides and fatty acids can be absorbed into the gut and transported by the blood throughout the body.

FAT from diet --> (bile salts) --> triglycerides --> (lipase) -->fatty acids and monoglycerides

Any thing that interferes with any of the steps along the way can cause MALABSORPTION. Liver problems where there is poor bile production, pancreatic problems where there is lack of lipase productions, drugs that interfere with either or both, short bowel syndrome following surgery where food passes right through or medications which block the production or function of lipase. All these can lead to malabsorption.