Fat malabsorption is a condition that results in a very limited ability of the body to absorb fats in the gastrointestinal tract. It can be caused by a number of underlying conditions, such as Crohn’s disease, chronic liver disease, pancreatic cancer, AIDS and HIV. Fat malabsorption results in weight loss, chronic diarrhea, fatty stools and deficiency symptoms of nutrients, particularly the fat-soluble vitamins. In addition, it is common to feel lethargic when you have fat malabsorption. Following some nutritional guidelines can help to restore good health. Discuss food choices with your doctor.