What happens when you eat fatty and greasy foods:
The digestion of fat begins in the mouth where the food you chew is mixed with a small amount of lingual lipase that is found in your saliva. Lingual lipase is a digestive enzymes that breaks fatty acids apart from triglycerides.
Once you swallow your food, digestion continues in the stomach. A small amount of lipase is also secreted in the stomach to continue the digestion of fat, but most fat digestion takes place in the small intestine.
Your liver produces bile, which is stored in the gall bladder until it's triggered by eating foods that contain fat. Bile is released into the small intestine where it works like a detergent to emulsify the fats into smaller droplets. This makes it easier for pancreatic lipase to get to the triglycerides.
The bile and lipase break fats down into smaller pieces that are absorbed into the blood stream. The bile, which contains cholesterol, is either re-absorbed into the blood or bound by soluble fiber in the intestine and eliminated in the stool. Eating foods with lots of soluble fiber helps keep your cholesterol levels healthy by grabbing more of the cholesterol from the bile and eliminating it from your body.
A healthy digestive system will absorb about 95 percent of the dietary fat that you eat. People with malabsorption disorders like celic sprue, pancreatic lipase deficiency and bile salt deficiency usually can't absorb fats properly.
Fats and Oils contain nine calories per gram. Your body takes the extra fatty acids and stores them as adipose tissue, which is better known as body fat. Adipose tissue can be broken down and turned into glucose when you need more calories -- that's why counting calories is important if you want to lose weight.
High-fat food also can result in pale-colored stool, a phenomenon called steatorrhea, which is essentially excess fat in the feces. A lot of people with irritable bowel syndrome need to stay away from foods high in fat, she says, including butter and cream because they can cause digestive problems.