Sitting around 8216;makes your posterior bigger8217;

This can explain why couch potatoes and other sedentary behaviour makes you fat when combined with a lack of exercise. But even those with healthy diet and exercise habits will be affected if they spend long periods sat behind a desk,say the researchers.

They found that preadipocyte cells 8211; the precursors to fat cells 8211; turn into fat cells and produce even more fat when subject to prolonged periods of 8220;mechanical stretching loads8221; 8212; the kind of weight we put on our body tissues when people sit or lie down.

By studying MRI images of the muscle tissue of patients paralysed by spinal cord injuries,they noticed that,over time,lines of fat cells were invading major muscles in the body,8217;The Daily Telegraph8217; reported.

This spurred an investigation into how mechanical load the amount of force placed on a particular area occupied by cells 8212; could be encouraging fat tissue to expand.

The researchers stimulated preadipocytes with glucose or insulin to turn them into fat cells. They then placed individual cells in a cell-stretching device,attaching them to a flexible,elastic substrate 8212; or underlying.