The Structure of Fat
You get the same amount of energy—9 kcal per gram—regardless of which type of fat is predominant. The difference between the various types of fat lies in their functions and effects on the body.
- Triglycerides consist of glycerol, which binds the three fatty acids into three long chains.
- Triglycerides make up the majority of the fat in our food.
- Triglycerides can be packed very tightly. This means that a lot of energy can be stored in a small
- space compared to sugar stores, which take up a lot of room and also absorb water.
The fatty acid that binds to the glycerol moiety can be:
- Saturated
- Monounsaturated – one double bond
- Polyunsaturated – two or more double bonds
Digestion and absorption
- When fat dissolves in water, emulsification occurs, which is a necessary process.
- Bile, which contains bile salts, dissolves or emulsifies fat.
- The enzyme lipase breaks down triglycerides into glycerol and free fatty acids
Metabolism
Fat is transported in the blood in the form of lipoproteins: chylomicrons, VLDL, LDL, and HDL
LDL = "bad" cholesterol
HDL = "good" cholesterol
LDL contains more cholesterol than HDL and supplies cells with cholesterol. It helps build cell membranes and hormones.When LDL levels in the blood are high, some of the LDL is taken up by macrophages in the walls of blood vessels. The accumulation of fat-filled macrophages in the vessel walls leads to cardiovascular disease. For this reason, LDL is called “bad cholesterol.”
One of HDL’s functions is to transport excess cholesterol from the cells to the liver. HDL also has antioxidant properties. High levels of HDL are associated with a lower risk of cardiovascular disease. For this reason, HDL is often referred to as “good cholesterol.”
The Functions of Fat
- It is a component of cell membranes.
- Fat is a building block for cholesterol, eicosanoids, and testosterone.
- It acts as an insulating material.
- Both fat-soluble vitamins A, D, E, and K, as well as essential fatty acids, are supplied through fat.
- Fat is an energy-providing nutrient that provides more energy per gram than carbohydrates, protein, and alcohol.
- Fat enhances flavors and aromas. A meal that’s too lean can, in that case, be very bland and uninteresting.
Is fat bad for you?
The right kind of fat is very important for our health—including for the immune system, cancer prevention, brain health, the nervous system, skin, and joints—as well as for preventing cardiovascular disease and diabetes.
The total fat content of the diet and the composition of that fat influence lipid metabolism and blood lipid levels. The composition of the fat is more important than the total amount of fat we consume. When saturated fat and trans fat are replaced with monounsaturated and polyunsaturated fats, LDL levels decrease. If total fat intake decreases, HDL levels also decrease.
It is important to note that HDL levels can also be increased through regular physical activity.
No restrictions?
- Fat in food is not the same as body fat.
- The risk of developing illnesses is lower if:
- The fat has not been processed or heat-treated
- The fat content is correct
Always include fat in every meal—but in moderation!