Increased LDL
One of the major effects of saturated fat on the body is to increase synthesis of low density lipoprotein, or LDL. This is colloquially referred to as "bad cholesterol," but is in fact simply cholesterol that has been packaged by the liver and is being sent to cells for uptake. Drs. Reginald Garrett and Charles Grisham explain in their 2007 book "Biochemistry" that cells will only take in LDL from the bloodstream in accordance with their needs. If saturated fat consumption leads to high blood levels of LDL, cells stop taking up cholesterol, and the excess remains in the blood. This high level of blood cholesterol can have other cardiovascular effects.
Atherosclerosis
When cholesterol builds up in the bloodstream and cells stop taking it up, the cholesterol can end up forming plaques inside arteries. This leads to narrowing and hardening of the arteries--a disease process called atherosclerosis. According to the Mayo Clinic, atherosclerosis--sometimes called arteriosclerosis--is associated with poor cardiovascular health for many reasons. Not only do narrowed blood vessels fail to deliver blood as efficiently as healthy vessels, but also, hardened arteries can crack and tear, leading to blood clot formation. Clots can then travel through the vascular system and lodge in small vessels, blocking blood flow completely.
Heart Attack and Stroke
Ultimately, high levels of saturated fat intake are associated with increased risk of heart attack and stroke. According to Dr. Lauralee Sherwood in her 2004 book "Human Physiology," this is because when hardened arteries form blood clots that break off and travel through the vessels, the clots are most likely to lodge in the vessels that feed either the heart or the brain. If brain tissue is denied oxygen, it begins to die; this is a stroke. The heart muscle, if denied oxygen, also dies, leading to a portion of the heart that can no longer function. This is called a heart attack, and can vary in severity from mild to life-threatening.