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Fats: Essential Energy-Supplying Nutrients

Fats (also called lipids) are natural substances that don't mix with water. They are very important for your body to work correctly.

The main kinds are:

  • Triglycerides: Most of the fat we eat and store is this type. They are made of three fatty acid parts connected to a glycerol part, mainly used for energy.

  • Phospholipids: These are key building blocks for all cell walls, helping to control what goes in and out of cells. They also help carry fat in your blood.

  • Sterols: Cholesterol is the most famous sterol. It's important for keeping cell walls strong and for making vital body chemicals like hormones (e.g., testosterone, estrogen) and vitamin D.

Some fats are called 'essential fatty acids' because your body can't make them, so you must get them from food. These include:

  • Omega-6 fatty acids: Like linoleic acid, found in vegetable oils (e.g., corn, soybean, sunflower oil).

  • Omega-3 fatty acids: Like alpha-linolenic acid (ALA) from plants (e.g., flaxseeds, walnuts) and other types like EPA and DHA from fatty fish (e.g., salmon, mackerel). These are very important for health.

Fats do many important jobs:

  • Give energy: They provide a lot of energy (9\ calories from each gram), more than carbs or protein.

  • Help absorb vitamins: They help your body take in and use important vitamins (A, D, E, K).

  • Build cells: They are part of your cell walls.

  • Protect organs: They act as a cushion around your organs.

  • Keep you warm: A layer of fat under your skin helps keep your body warm.

  • Make food satisfying: They make food taste good and help you feel full.

Most fat digestion happens in your small intestine. Your liver sends out a liquid called bile (stored in the gallbladder) to break down big clumps of fat into smaller drops, making them easier to digest. Then, digestive juices from your pancreas break down triglycerides into smaller pieces. These smaller fat pieces, with the help of bile, form tiny packages called 'micelles.' Micelles carry these fats to the cells lining your gut. Inside these cells, these fat pieces are put back together to form triglycerides, and then wrapped in protein to make 'chylomicrons.' These chylomicrons are too big to go straight into your blood, so they travel through a special network (the lymphatic system) before finally reaching your bloodstream.

Health experts suggest that 20-35\% of your daily calories should come from fat. It's important to eat less saturated and trans fats because too much of them can raise 'bad' cholesterol (LDL), which is a big risk for heart disease. On the other hand, getting enough essential omega-3 fats (like about 1.6 grams a day for men and 1.1 grams for women for alpha-linolenic acid) is very good for your heart and brain. While studies are still looking into it, eating a lot of certain types of fat might also be linked to some cancers, especially prostate cancer.