Thousands of years ago, our ancestors often faced long periods without food. Their bodies had a smart survival mechanism — any extra glucose (sugar) they ate was stored as fat. Later, when food was scarce, that fat was broken down into glucose again to provide energy.

Fast forward to today. Food is available in abundance, but our lifestyle has become more sedentary. The body’s fat-storing mechanism hasn’t changed, but our environment has.

So, what happens when we take in more calories than we burn?
The excess glucose gets converted and stored as fat. And the key player in this process is insulin.

Here’s how insulin does it:

1. It helps fat cells in our body (especially in fat tissue which is called as adipose tissue ) take up extra glucose and convert it into fat and then store it. 

2. It increases the activity of fat-building enzymes.

3. It blocks the enzymes responsible for breaking down fat.

The final result? More fat gets stored in our fat tissue (adipose tissue) whenever glucose levels are high.

Now, imagine a situation where insulin doesn’t work properly — a condition called insulin resistance.

In this case, fat storage in adipose tissue is reduced, and fat breakdown increases. The fatty acids released into the blood now start depositing in places they shouldn’t — mainly in organs like the liver and muscles. This is known as lipotoxicity. 

Some other factors that play a role this process are obesity or overweight, Genetics, mitochondrial dysfunction and gut microbiota.