Why we get FAT?

Why we get Fat?

If this is your first visit to the blog, please go to Introduction or Index of All Posts.

In this post, we will discuss the following topics related to “Why we get Fat” actually?

  1. Role of Fat
  2. Types of Fat
  3. Measuring Body Fat
  4. Factors that affect Fat metabolism (e.g. Gender, Age etc.)
  5. Metabolism of Fat (or what happens when we eat/drink)
  6. Role of Stress in Fat metabolism
  7. What can be done to reduce fat deposition

For the purposes of this blog – a Fat is the same as a “Fatty Acid” (remember Omega-3 fatty acids and fish oil !!)

1. Role of Fat

  1. A certain amount of Body Fat is essential. Typically an average male contains approx 15-20% of Fat and an average female contains between 20-25% of Fat. Assuming a body weight of 80 kgs that is approximately 15 kgs of Fat. The essential fat for men is approx. 5% and for women is approx. 10%. So, to be sure, you cannot have zero fat without harming yourselves
  2. Fat is stored energy and is a more efficient (and condensed) form of energy storage compared to Glucose (or Glycogen). 1 gm of Fat has approx 9 calories and 1 gm of Glucose yields closer to 4 calories
  3. Fat also helps to provide insulation as well as padding (to prevent shock and injury)

2. Types of Fat

There are many types of Fat depending on the context we use. Let us look at a few..

2.1 In the Human Body

In the Human body, there are two types of fat – 1) Sub-cutaneous and 2) Visceral

Sub-cutaneous (beneath the skin : This is considered to be harmless generally. Mostly for insulation purposes.

Visceral – Packed between organs mostly in the abdomen. Too much of this is considered to be harmful. The focus of the blog will be on Visceral fat.

Note: Most of the human Fat is white. There is something known as “Brown Fat” which is present in mammals – mostly newborns and hibernating animals. We will ignore this for now.

2.2 In Nature

In general fats in nature occur in 3 forms – Saturated (supposed to the bad one), Poly-unsaturated and Mono-unsaturated (supposed to be the good ones). (For the record I don’t agree with this good and bad categorisation).

In Saturated Fats the carbons are fully “saturated” with Hydrogen atoms. There is no room for any more Hydrogen atoms generally and has the maximum number of Hydrogen atoms bonded. Most of animal fats and milk products belong to this category as well as tropical oils like Coconut oil, palm oil etc. They are also mostly made up of Tri-glycerides (we will come to this soon)

In Unsaturated fats, there are some double bonds which means there is room for some more Hydrogen atoms than that are already present. Foods containing unsaturated fats include Olive oil, Avocado, Nuts etc. Some part of meat is also made up of unsaturated fats.

2.3 Trans Fats and Hydrogenated Fats

Fats that are available in nature generally (not always) have the bonds on the same side (called “cis”). Trans Fats on the other hand have bonds that are on the opposite side. Typically these are created by taking oils and blasting Hydrogen at extremely high speed. This process solidifies the oils which increases their trans-portability and storage. It also makes it easy to apply on bread (an olive spread is definitely more convenient compared to applying olive oil in liquid form on a slice of bread !!!). So this is done mostly for commercial reasons.

Examples of Trans Fats (and partially hydrogenated oils) are margarine, most of the spreads, Vanaspati (Dalda) etc.

Avoid Trans Fats and Hydrogenated oils like the plague. They are very harmful !!

3. How do we measure Fat in the body

There are many ways of measuring body fat. In descending order of their accuracy they are as follows:

  • DEXA scan: Based on x-ray absorptiometry. Very accurate. Expensive and not for common use.
  • Weighing in Water: Very accurate measurement that is based on submerging the person in a customised water tank. Expensive, Impractical and not for normal or regular use
  • Calipers: Measuring skin folds at multiple points on the body. Slightly awkward and somewhat accurate
  • Special weighing scales or bathroom scales with fat measurement capability: These are based on the electrical resistance. Unreliable and are dependent on hydration levels etc.
  •  Lastly the “Anthropometric” method based on a few tape measurements and standard parameters. Very crude and approximate. But the easiest of the lot.

Pls visit this link which has a Body Fat calculator used by US Navy


There is a helpful table at the bottom showing the categories and the levels.

Most of all, the easiest way is to just be conscious of your trousers and belts. If you need an extra hole in the belt (on the wrong side) then perhaps things are not going too well. Also if you need to buy the next higher size trousers it does not bode too well either. But if you are dropping trouser sizes and moving into the inner holes on the belt then you perhaps are doing well.

Bottom line: If you are a man try to stay around 12 – 17% or so and if you are a woman try staying around 25% if you want to be healthy and fit.

4. Factors that affect Fat Metabolism

The following factors seem to be affect the fat metabolism in general.

  • Gender
  • Age
  • Food and Drink consumed
  • Stress Levels
  • Sepcialised Exercise (not regular aerobic exercise for 30 mins a day)

4.1 Gender

In general women tend to have more fat (as a proportion – not absolute weight) than men – on average. 25% of fat in women is not uncommon or unhealthy whereas the same level could potentially be deemed unhealthy in men.

I am not sure why this is the case but there are suggestions that this could be evolutionary (for the sake of the babies etc.). But that does not seem correct since there is a tendency to put on more fat in women after menopause.

Also Fat is stored mostly around the waist and hip for men but mostly around the thighs and buttocks in women.

4.2 Age

Again there is a general tendency to be fatty as one ages – both across men and women. Several explanations are out there but the most likely one could be related to Insulin Resistance.

4.3 Food and Drink consumed

Part 3 of the post will deal with this.

4.4 Stress Levels

There are some suggestions that increased stress levels resulting in increased Cortisol and Adrenaline hormone production interfere with the general metabolism and fat metabolism (by impacting insulin levels). Certainly there is some evidence that increased stress levels cause Cardio-vascular diseases.

4.5 Exercise

As discussed in the previous post, regular aerobic exercise for 30 mins a day is unlikely to make a huge impact on either weight or fat levels. But specialised exercise regimes loosely called “High Intensity Interval Training” (HIIT) are supposed to increase insulin sensitivity thereby impacting fat metabolism. I intend to write a detailed post later but for now you can look at the following links if you are interested.



Continued in Why we get Fat – Part 2


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