Cholesterol is a fat (also called a lipid) that your body needs to work properly. Too much bad cholesterol can increase your chance of getting heart disease, stroke, and other problems.

Causes

There are many types of cholesterol. The ones talked about most are:

Total cholesterol -- all the cholesterols combined

High density lipoprotein (HDL) cholesterol -- often called "good" cholesterol

Low density lipoprotein (LDL) cholesterol -- often called "bad" cholesterol

For many people, abnormal cholesterol levels are partly due to an unhealthy lifestyle. 

Being overweight

Lack of exercise

Some health conditions can also lead to abnormal cholesterol, including:

Diabetes

Kidney disease

Polycystic ovary syndrome

Pregnancy and other conditions that increase levels of female hormones

Underactive thyroid gland

Medicines such as certain birth control pills, diuretics (water pills), beta-blockers, and some medicines used to treat depression may also raise cholesterol levels. Several disorders that are passed down through families lead to abnormal cholesterol and triglyceride levels.