Fats are one of the three main macronutrient groups in human diet, along with carbohydrates and proteins, and the main components of common food products like milk, butter, tallow, lard, bacon, and cooking oils.
Fats are a major and dense source of food energy, fat has 9 calories per gram, more than 2 times the number of calories in carbohydrates and protein, which each have 4 calories per gram.
Fats are the slowest source of energy but the most energy-efficient form of food. The body stores any excess energy as fat in the abdomen (omental fat) and under the skin (subcutaneous fat) to use when it needs more energy. The body may also deposit excess fat in blood vessels and within organs, where it can block blood flow and damage organs.
Fats are also needed to keep the skin and hair healthy and also helps us absorb vitamins A, D, E, and K, the so-called fat-soluble vitamins. Fat also fills our fat cells and nsulates the body to keep it warm.
The human body can produce the fat that it needs from other food ingredients, except for a few essential fatty acids that must be included in the diet.
Carbohydrates are the quickest, and fats are the slowest in energy supply. Carbohydrates, proteins, and fats are digested in the intestine, where they are broken down into their basic units - carbohydrates into sugars, proteins into amino acids and fats into fatty acids and glycerol.
The most important elements in the chemical makeup of fats are the fatty acids. The molecule of a fatty acid consists of a carboxyl group HO(O=)C− connected to an unbranched alkyl group ?(CHx)nH: namely, a chain of carbon atoms, joined by single, double, or (more rarely) triple bonds, with all remaining free bonds filled by hydrogen atoms.
Types of FatThere are two main types of fats - saturated and unsaturated. A saturated fat has no double bonds in its chemical structure, whereas an unsaturated fat has one or more double bonds.
1) Unsaturated fatsUnsaturated fats, which are liquid at room temperature, are considered beneficial fats because they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play a number of other beneficial roles.
Unsaturated fats are predominantly found in foods from plants, such as vegetable oils, nuts, and seeds.
There are two types of "good" unsaturated fats -
1.1) Mono-unsaturated fatsMonounsaturated fats are simply fat molecules that have one unsaturated carbon bond in the molecule, this is also called a double bond. Oils that contain monounsaturated fats are typically liquid at room temperature but start to turn solid when chilled i.e. Olive oil.
Monounsaturated fats are found in high concentrations in: Olive, peanut, and canola oils, Avocados, Nuts such as almonds, hazelnuts, and pecans, Seeds such as pumpkin and sesame seeds.
1.2) Poly-unsaturated fatsThe two major classes of polyunsaturated fats are omega-3 and omega-6 fatty acids. Both are essential fatty acids that your body needs for brain function and cell growth. Yet, our body cannot make essential fatty acids, so we must get them from your diet.
Polyunsaturated fats are found in high concentrations in: Sunflower, corn, soybean, and flaxseed oils, Walnuts, Flax seeds, Fish Canola oil.
Good sources of omega-3 fats include: fish, flax seeds, walnuts, and canola or soybean oil. ? but these give a less active form of the fat than fish do.
Plant-based oils are high in omega-6 fatty acids - with the exception of coconut and palm oil, which contain a high percentage of saturated fats and are solid at room temperature. Example: Safflower oil, Grapeseed oil, Flaxseed oil, Sunflower oil, Poppyseed oil, and Soybean oil.
2) Saturated fatsSaturated fats are saturated with hydrogen molecules and contain only single bonds between carbon molecules. This saturation of hydrogen molecules results in saturated fats being solid at room temperature, unlike unsaturated fats, such as olive oil, which tend to be liquid at room temperature.
Saturated fats are unhealthy because they increase LDL (Low-density lipoprotein) or "bad" cholesterol levels in the body and increase the risk of heart disease.
The biggest sources of saturated fat in the diet are: ice cream, pizza and cheese, whole and reduced fat milk, butter and dairy desserts, meat products (sausage, bacon, beef, hamburgers, cookies and other grain-based desserts, a variety of mixed fast food dishes.
Trans FatsTrans fatty acids (trans fats) are made by heating liquid vegetable oils in the presence of hydrogen gas and a catalyst, to make them stay solid at room temperature - the process is called hydrogenation.
In simple words trans fat is liquid oils turned into solid fats during food processing, there is also a small amount of trans fat that occurs naturally in some meat and dairy products.
Trans fats are the worst type of fat for the heart, blood vessels, and rest of the body. - They increase LDL ("bad" cholesterol) and decreasing HDL (High-density lipoprotein - "healthy" cholesterol).
Trans fatty acids are used as preservative in packaged food items. Industrially produced trans fatty acids (TFAs) or artificial trans fats or partially hydrogenated fats are hazardous to the health.