In addition to Carbohydrates and proteins, fats are a major source of energy, providing structure and cushion to cells and membranes. Fats are more energy dense than carbohydrates and proteins and contain 9 calories per gram, in contrast to 4 calories per gram of carbohydrates and proteins. Fats are fundamental part of a healthy, balanced diet and are the body’s only source of essential fatty acids, since these can not be made by the body. Similar to carbohydrates and proteins, unused fat is converted into body fat and stored as residual energy sources.

The following are the functions of Fats in the body:

• Prevent damage to the organs by providing cushion.
• Absorb nutrients such as vitamins A, D, E, and K
• Maintain normal levels of cholesterol and blood pressure. 
• Store and provide energy. 
• Support cell growth.

According to the American Heart Association, there are four major dietary fats in food including:

• Saturated fats
• Trans fats
• Monounsaturated fats
• Polyunsaturated fats)

Monounsaturated and polyunsaturated fats are types of unsaturated fats.The different types of fat have varying chemical composition and structures, and consequently, vary in their physical properties. Based on these, saturated fats and trans fats are considered ‘bad’ and appear solid in room temperature while unsaturated fats- monounsaturated fats and polyunsaturated are considered ‘good’ fats remain liquid in room temperature. Fats play an essential role in determining the cholesterol level of the body. Good and bad fats have various effects on the body’s cholesterol level. For instance, diets high in good fats increases the body’s good cholesterol level, also called high-density lipoprotein (HDL). In the same vein, diets high in bad fats increases the body’s bad cholesterol known as low-density lipoprotein (LDL).

Sources of good fat include tofu, flaxseed, avocados, olives, soy, sesame seed, nuts, dairy, fatty fish, canola, and coconut. On the contrary, baked foods, pizza dough, chips, vegetable shortening, fried foods, margarine, hydrogenated or partially hydrogenated vegetable oil are sources of bad fat, particularly trans-fat. Although both bad fats, Trans fats are worse than saturated fats and are not recommended for a healthy diet. However, red meat, chicken skin, ice cream, cheese, cream, butter are sources of saturated fats which are only recommended in small quantities, even though they are considered  bad fats and increase bad cholesterol.

As advised by the World health Organization, Centers for Disease Control and Prevention and National Health Services, it is important to consume more polyunsaturated and monounsaturated (good) fats than saturated and trans (bad) fats. Bad fats, particularly Trans fats have been shown to increase the risk of heart disease and increase levels of bad cholesterol (LDL). In contrast, Unsaturated fats (monounsaturated and polyunsaturated fats) reduce the risk of heart attacks by decreasing the levels of bad cholesterol (LDL) cholesterol and increasing the good cholesterol level (HDL).