You may have read an article in the last week or so about some Sydney researchers reporting on where fat goes when you lose weight.
The researchers from the University of New South Wales stated that despite a worldwide obsession with diets and fitness regimes, many health professionals cannot correctly answer the question of where body fat goes when people lose weight.
According to the scientists, the correct answer is that most of the mass is breathed out as carbon dioxide. It goes into thin air.
In the research paper, published in the British Medical Journal, the authors show that losing 10 kilograms of fat requires 29 kilograms of oxygen to be inhaled and that this metabolic process produces 28 kilograms of carbon dioxide and 11 kilograms of water.
The scientists approach to the biochemistry of weight loss was to trace every atom in the fat being lost.
If you follow the atoms in 10 kilograms of fat as they are 'lost', 8.4 of those kilograms are exhaled as carbon dioxide through the lungs. The remaining 1.6 kilograms becomes water, which may be excreted in urine, faeces, sweat, breath, tears and other bodily fluids.
"This violates the Law of Conservation of Mass. We suspect this misconception is caused by the energy in/energy out mantra surrounding weight loss," the researchers state.
Some respondents thought the metabolites of fat were excreted in faeces or converted to muscle.
One of the most frequently asked questions the authors have encountered is whether simply breathing more can cause weight loss. The answer is no. Breathing more than required by a person's metabolic rate leads to hyperventilation, which can result in dizziness, palpitations and loss of consciousness.
One of the things I think the researchers failed to state clearly is that carbon dioxide and water are produced as a result of metabolising fat. And while the fat isn't converted to energy, it is in the process of using fat for energy that the body creates carbon dioxide and water.
And the important point to remember is that the fitter you are, the better your muscles and cells are at using fat, creating carbon dioxide and producing energy.
