London, March 21 (IANS): You have heard about obesity or accumulation of fat but do you know that nutrition is not the only factor driving obesity in our kids?

According to researchers, the mechanics of 'cellular expansion' plays a pivotal role in fat production.

To understand how obesity develops, a team from Tel Aviv University in Israel used state-of-the-art technology to analyse the accumulation of fat in the body at the cellular level.

“We wanted to find out why a sedentary lifestyle results in obesity, other than making time to eat more hamburgers," said professor Amit Gefen from Tel Aviv University's department of biomedical engineering.

"We found that fat cells exposed to sustained, chronic pressure - such as what happens to the buttocks when you are sitting down - experienced accelerated growth of lipid droplets, which are molecules that carry fats,” Gefen added.

Contrary to muscle and bone tissue, which get mechanically weaker with disuse, fat depots in fat cells expanded when they experienced sustained loading by as much as 50 percent. This was a substantial discovery.

The researchers discovered that, once it accumulated lipid droplets, the structure of a cell and its mechanics changed dramatically.

Using a cutting-edge atomic force microscope and other microscopy technologies, they were able to observe the material composition of the transforming fat cell, which became stiffer as it expanded.

This stiffness alters the environment of surrounding cells by physically deforming them, pushing them to change their own shape and composition.

“When they gain mass and change their composition, expanding cells deform neighbouring cells, forcing them to differentiate and expand,” he explained.

This proves that you are not just what you eat. You are also what you feel - and what you are feeling is the pressure of increased weight and the sustained loading in the tissues of the buttocks of the couch potato.

If you can learn to control the mechanical environment of cells, you can then determine how to modulate the fat cells to produce less fat, Natan Shaked from Tel Aviv University noted.

The team is now creating a platform to develop new therapies and technologies to prevent or even reverse fat gain, said the research published in the Biophysical Journal.