A new article in the British Medical Journal has revealed majority of weight loss is exhaled carbon dioxide.
A new study replaces all preconceptions of losing weight, and have now revealed the real process of what happens to fat.
Excess dietary carbohydrates and protein are converted to a type of fat called triglyceride…Triglycerides are comprised of three types of atom: carbon, hydrogen and oxygen. Triglyceride molecules can be broken down only by unlocking these atoms, through a process known as oxidation. 
The researchers of this study found that when 10 kg of fat were oxidized, 8.4 kg were converted and excreted as carbon dioxide (CO2) via the lungs, and 1.6 kg became water (H20).
In order for 10 kg of human fat to be oxidized, the researchers calculated that 29 kg of oxygen must be inhaled. Oxidation then produces a total of 28 kg of CO2 and 11 kg of H20.
Although the science has always been there, no one had thought to look closely at the numbers. The same advise still stands for weight loss; to eat less and move more.
The results suggest that the lungs are the main excretory organ for weight loss, with the H20 produced by oxidation departing the body in urine, feces, breath and other bodily fluids. 
The weight is only kept on by the carbon being replaced by more food intake. If we replace just one hour of rest with one hour of exercise we up our exhaled carbon by another 40g, meaning on average a day, we exhale 240g of carbon dioxide.
Although you may still stock up on carbon this Christmas, no fret, we just have to manage our levels of food so our bodies have time to do the breakdown.
 McIntosh, J. (2014). Majority of weight loss occurs ‘via breathing’. Medical News Today. Available at: http://www.medicalnewstoday.com/articles/287046.php [Accessed 17 Dec. 2014].