FAT – Definition | Significance | Types | RDA | Sources | Functions

Fat is one of the building blocks of the body. The average person is made up of between 15 and 30 percent of fat!

However, yet for decades, we have unjustly reduced dietary fat and diligently followed a diet low in fat. That almost always equates into a high-sugar and high-refined-carb diet that contributes to insulin resistance, obesity, and many more problems.

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Not all fats are bad. A certain amount of fats is an essential part of a healthy balanced diet. We need fats to our nerve cells, brain, and skin, to protect the vital organs of the body and help control our body temperature.

Fat also provides energy and adds flavor and texture to food. The problem is when we eat too many fats or too much of the unhealthiest types of fats. 

In this article, I will discuss Definitions, Significance, Types, RDA, Sources, Functions, and some Misconceptions about Fats.

★ So, first let me introduce What are FATS?

Simply, fats are one of the three macronutrients. Others are Carbohydrates and Proteins. Our body needs a decent amount of good fats to function properly and prevent diseases.

Fats are made up of lipid molecules, while lipids are made up of long-chain fatty acids. And these fatty acids are made up of carbon, hydrogen, and oxygen.

Some fats are essential for the body because the body cannot produce them.

Due to the long fatty acid chain, our body take more time to break them as compared to carbs and proteins.

One gram of fats contains 9 calories. For this reason, many health departments suggest not more than 30-35 % of total calories should come from fats. While many of us consume more than 45% (sometimes a lot more).

Dietary fats make food tastier and improve flavor. Fats are also necessary for absorption of fat-soluble vitamins like vitamin A, D, E, and K.

★ Significance of Fat

1. Digestion

Fats are not soluble in the blood, so that bile acids from the cholesterol produced in the liver emulsify it to make it bioavailable. Fat stores fat-soluble vitamins A, D, E and K in liver tissue. For the process of fat breakdown, multiple organs are involved such as stomach, duodenum, liver, gallbladder, pancreas and small intestine. So it remains long and keeps you satiated.

2. Transport

Fats are part of all cell membranes in the body. It helps transport nutrients and metabolites substances through cell membranes.

3. Conversion

The body uses fats for everything from hormones to activating the immune function.

4. Energy Extraction

Between meals or when glucose is not available, triglycerides are broken down and metabolized for energy. So energy is always available to your brain because of fats.

5. Nervous System

The axon is the part of a nerve (neuron) that transmits electrical signals from the brain through the body to initiate all functions. The protective coating is axonal myelin sheath and it is made up of 80% lipids (fats) that must be supplied by the diet.

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★ Types of FAT

There are two types of fats: Dietary fat (consumable fats) and body fat (stored fats).

NOTE: It’s not recommended to consume animal fat or stored fat.

➀ Dietary fat or Consumable Fat

There are two types of Dietary fat: Saturated and Unsaturated.

1. Saturated Fats

Certain fatty acids have as many hydrogen atoms as the carbon chain can hold. They are called saturated fat. Because they are saturated by hydrogen and do not contain any double bonds. This is also called ‘solid fat’. Because they are generally solid at room temperature (like butter, ghee etc).

Saturated fat is found commonly – but not exclusively in animal products like milk, meat, cheese etc.

This fat can raise your LDL (Low-Density Lipoproteins) or bad cholesterol level when consumed in large amount. This may increase the risk of cardiovascular diseases and type 2 diabetes. Health experts recommend less than 10% of total calories should come from saturated fat.

2. Unsaturated Fats

Those fatty acids have the capacity to accommodate more hydrogen atoms, are called Unsaturated fat. These fat contains one or more double bonds and is not saturated by hydrogen. Unsaturated fat is generally liquid at room temperature (like oils).

These fats are good for health because it may help to lower the LDL or bad cholesterol level. They are commonly found in avocados, nuts, peanuts, seeds, fish, and canola oil.

► Unsaturated fats are of two types: Monounsaturated fat and Polyunsaturated fat.

1. Monounsaturated Fats

Having one unsaturated chemical bonds (mono = one). Monounsaturated fats are found mostly in avocado, peanuts, and olive oils. It can increase HDL (High-Density Lipoproteins) or good cholesterol while decreasing LDL (Low-Density Lipoproteins) or bad cholesterol level in blood.

2. Polyunsaturated Fats

Having more than one unsaturated chemical bonds (poly = many). Polyunsaturated fats are found mostly in plant-based foods and oils. It also lowers the LDL or bad cholesterol level, but unlike monounsaturated fat, it also lowers the HDL or good cholesterol level.

► Polyunsaturated fats are of two types: Omega 3 and Omega 6.

i) Omega 3

Found in animals like fatty fish (salmon, tuna, trout, mackerel, sardines, and herring) as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). It also found in plants like flaxseed (ground), oils (canola, flaxseed, soybean), and nuts and other seeds (walnuts, butternuts, and sunflower) as alpha-linolenic acid (ALA).

A healthy diet should contain 8 ounces of Omega 3 per week or 250 mg per day. Omega 3 fatty acids are beneficial for our brain as well as the heart. It decreases the risk of coronary heart disease by lowering the cholesterol level in arteries and reducing inflammation.

ii) Omega 6

Found in vegetable oils like soybean oil, corn oil, and safflower oil.

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➁ Body Fats or Stored Fats

There are four types of body fats. Visceral fats, Subcutaneous fats, Brown fats, and White fats.

1. Visceral Fats

These fats are located deep inside the body, usually around organs and muscles. Visceral fats are the unhealthiest fat because this can increase the risk of diabetes, heart disease, insulin resistance and even dementia. When we lose weight by reducing calorie intake and increasing physical exercise, we are losing visceral fats as well as white fats.

2. Subcutaneous Fats

This is found under the skin and we even feel and measure this by skinfold calipers. Subcutaneous fat is not particularly unhealthy because it does not interfere with muscle and organs. Subcutaneous fat in the belly is more dangerous compared to the thighs and buttocks.

3. Brown Fats

This fat is healthy for babies and children. Because brown fat produces heat which warms the body. When stimulated (usually by cold) brown fat actually burns calories as well as white fats. Children and lean people have more brown fat than the rest of stored fats.

4. White Fats

The main function of the white fat is to store energy and produce a hormone, like adiponectin. Which makes the cells more sensitive to the hormone insulin. For this reason, white fat makes us less susceptible to diabetes and heart diseases. But when people become obese, adiponectin production slows down or shuts down.

★ What is TRANS-Fat?

Trans fatty acids or trans fats are of two types: natural and artificial.

Natural trans fat is found in guts of some animals. While artificial trans fat are made in the industrial process that adds hydrogen to unsaturated fat to make them saturated or solid.

Because of this reason artificial trans fat is also called hydrogenated vegetable oils. It increases LDL while decreases HDL. So you should avoid trans fat.

This fat is found in packaged foods like biscuits, cakes etc. 

★ What is Total Fat?

You will find it written on the labels of all packaged foods and beverages.

Total fat = Saturated fat + Monounsaturated fat + Polyunsaturated fat + Trans fat.

Total Fat
Image credit: http://blog.alz.org/dietary-saturated-fat-the-risk-of-alzheimers/

★ Recommended Daily Allowance

The amount of fat you need each day depends on your calorie needs. The Institute of Medicine recommends that adults consume between 30 and 35 percent of their daily calories from fat.

For example, you would need between 36 and 62 grams of fat with a diet of 1,600 calories a day, from 44 to 78 grams if you eat a diet of 2,000 calories per day and 58 to 101 grams of fat by eating 2,600 calories a day.

According to the US Department of Agriculture, adult men need between 2,000 and 3,000 calories a day, while women need between 1,600 and 2,400 calories a day to maintain a healthy weight. Calorie needs are based on their size and activity level.

Based on these guidelines, limit your intake of saturated fats to 18 grams or less than 1,600 calories a day, consuming 22 grams if you eat 2,000 calories a day and 29 grams or less of consuming 2,600 calories a day.

Some athletes like bodybuilders who try to minimize body fat require a lower percentage of calories from fat than non-athletes. According to an article published in an edition of “Sports Medicine” in 2004, 15-20 percent of total calories should come from fat during the off-season. This is equivalent to between 50 and 67 grams of fat a day when they consume a 3,000 calorie diet and 67 to 89 grams of fat a day when they consume 4,000 calories.

★ Sources of Fats

Good fats – sources of MUFA, PUFA & Omega 3 fatty acids.

Good FatsServing sizeAmount of Fat
Almonds6 nos4.5g
Avocados2 Tbsp4.5g
Olive oils1 tsp4.5g
Cashews6 nuts4.5g
Peanuts10 nuts4.5g
Safflower oil1 tsp4.5g
Soya bean oil1 tsp4.5g
Salmon, trout1.5 oz4.5g
Walnuts2 whole or 4 halves4.5g
Sunflower oils1 tsp4.5g


Bad fats – sources of saturated & trans fats.

Bad FatsServing sizeAmount of Fat
Butter1 pat or 1 “ square4.06g
Cream1 Tbsp4.5g
Ghee1 tsp5g
Haldiram snacks2 Tbsp5g
Bacon1 slice4.5g
Sausage break fast1 oz8g
French fries1.3 oz ( 38 g)6g
Peanut butter1 ½ tsp4.5g
Creamy Salad1 tbsp5g
Pork Mutton & Chicken1 oz8g


★ Functions of Fats

1. Concentrated Source of Energy

Each gram of fat provides about 9 calories of energy. This is more than double the amount of energy supplied by a gram of carbohydrates or proteins. Usually, few fats are used to meet the energy needs of the body and the rest is stored under the skin in the abdominal region.

2. Safety Valve

You do not feel hungry for a long time after taking fats. This is because fats remain in the stomach longer and take more time to digest. 

3. Insulation and Padding

A layer of fats remains stored under the skin and acts as an insulator and keep the body warm. A layer of fats is also present in the organs of the body like kidney and heart. This serves as padding and protects them against injury.

4. Carrier of Vitamins

Some vitamins are fat soluble and fat serves as carriers for them aid in their absorption.

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★ How Are Fats Digested?

A secretion from the liver called bile helps in fat digestion by breaking fats into smaller droplets. These droplets are broken into fatty acids and glycerol and get transported through blood circulation. Blood carries them to cells where they are broken to provide energy or stored under the skin.

★ Misconceptions

People who try to lose weight often think that eating less fat is the best way to lose weight. But this is not true. Unsaturated fats contain essential fatty acids and can be found in blue fish, nuts, olive and canola oils, and avocados. These are “good” fats that improve your health and make up most of your daily fat calories.

So, now I think you got an overall idea about Fats. Please tell me how much you like this article. Comment down about you thoughts, doubts, questions and suggestions.

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FAT – Definition | Significance | Types | RDA | Sources | Functions
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A. R. Choudhury

Hi, This is A. R. Choudhury, a professional blogger & fitness expert from New Delhi, India.

Here at FabHealthFitness, I write about Health, Fitness, Bodybuilding, Supplements and Diet & Nutrition.

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