Fats in the Body

Generally there are two types of lipids (fats) in the body. The ones made by the body are called Cholesterol and the ones mostly come from our foods are called Triglycerides. Here are some information about them excerpted from a factsheet in the Bupa website of the UK:

Cholesterol

Cholesterol is found in every cell of the body. It is essential for good health, but a high cholesterol level in the blood may increase risk of cardiovascular diseases (CVD), which concern the heart and blood vessels.
Cholesterol is transported around the body in the blood attached to a protein. This combination of fat and protein is called a lipoprotein. Lipoproteins can be high density (HDL), low density (LDL) or very low density (VLDL), depending on how much protein there is in relation to fat.

LDL (Low Density Lipoprotein)

Most of the body's cholesterol is transported as LDL. This is made up of mostly fat and a small amount of protein. Too much LDL in the blood can cause cholesterol deposits to build up in the arteries, making it harder for the blood to flow through these blood vessels, and may increase the risk of CVD. That’s why LDL is sometimes referred to as " bad cholesterol".

HDL (High Density Lipoprotein)

A small amount of cholesterol is transported as HDL, which is mostly made up of protein and a small amount of fat. HDL actually helps prevent cholesterol deposits building up in the arteries. So HDL is sometimes referred to as "good cholesterol". Lower levels of HDL (compared with LDL) in the blood is associated with an increased risk of CVD.

Too high total cholesterol (TC) level is one risk factor for health problems. The relative amounts of HDL and LDL is often referred to as the TC:HDL ratio. Low ratio of TC:HDL (high HDL and low LDL) is desirable.

Triglycerides

Triglycerides are different types of fats. Energy that is eaten and not used immediately is converted into triglycerides and transported to fat cells for storage. Although most triglycerides are stored in fat tissue, low levels are also found in the blood. They are carried in the blood as VLDL.
A raised level of blood triglycerides together with high LDL can increase the risk of heart disease, particularly in people with diabetes.

High Cholesterol and Diets

As mentioned earlier, the main risk associated with high cholesterol is CVD. High cholesterol causes narrow blood vessels with fatty deposits called plaques. This can result in heart attacks, strokes and blood vessel problems.
Most cholesterol produced by your liver and a small amount comes directly from your diet. However, if your diet is high in saturated fats and cholesterol this can cause your liver to produce more LDL.
Healthy eating can reduce cholesterol. Your diet should be low in saturated fats in particular, and low in fat overall. Large amounts of cholesterol are found in a few foods, including eggs, offal such as liver, kidneys, and prawns. However, if you're already eating a balanced diet, you don't need to cut down on these foods.
It's also important to eat plenty of fiber, especially soluble fiber, which is thought to lower cholesterol. It's found in fruits, vegetables, beans and oats.