Melbourne, Dec 17 (IANS): To lose extra fat, all you have to do is breathe in and breathe out more during exercise or brisk walking, new research has revealed.

"Our calculations show that the lungs are the primary excretory organ for fat," the researchers said, noting that more than 80 percent of body fat can be exhaled away.

Excess carbohydrate or protein in the diet is converted to triglyceride, which consists of just three kinds of atoms - carbon, hydrogen and oxygen.

Shedding unwanted fat requires unlocking the atoms in triglyceride molecules by a process known as oxidation, the researchers explained.

"Losing weight requires unlocking the carbon stored in fat cells, thus reinforcing that often heard refrain of 'eat less, move more," said researchers Ruben Meerman and Andrew Brown from University of New South Wales in Australia.

They discovered that when 10 kg of fat are fully oxidised, 8.4 kg departs via lungs as carbon dioxide (CO2). The remaining 1.6 kg becomes water (H2O).

Their analysis showed that the inhaled oxygen required for this metabolic process weighs nearly three times more than the fat being 'lost'.

To completely oxidise 10 kg of human fat, 29 kg of oxygen must be inhaled producing a total of 28 kg of carbon dioxide and 11 kg of water.

"Keeping the weight off simply requires that you put less back in by eating than you have exhaled by breathing," the authors explained.

The study appeared in the British Medical Journal.