In its latest news update, the
Blackmores Institute- fostering research and education into natural health for health care professionals- has highlighted recent research into the role of the lungs in weight loss.
It seems that the lungs are the primary excretory organ for weight loss.
Blackmores Institute- About the research
Human fat cells store 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.
By tracing every atom's pathway out of the body, the authors discovered that when 10 kg of fat are fully oxidised, 8.4 kg departs via the lungs as carbon dioxide (CO2). The remaining 1.6 kg becomes water (H2O).
The researchers' analysis shows 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.
"None of this biochemistry is new, but for unknown reasons it seems nobody has thought of performing these calculations before," say the authors. "The quantities make perfect sense but we were surprised by the numbers that popped out."
"These results show that the lungs are the primary excretory organ for weight loss," they add. "The water formed may be excreted in the urine, faeces, sweat, breath, tears, or other bodily fluids and is readily replenished."
"The exhaled carbon can only be replaced by eating food or consuming beverages such as milk, fruit juices or sugar-sweetened drinks," the authors say.
"Keeping the weight off simply requires that you put less back in by eating than you've exhaled by breathing," explain the authors.
Replacing one hour of rest with exercise that raises the metabolic rate to seven times that of resting by, for example, jogging, removes an additional 40 g of carbon from the body, raising the total by about 20% to 240 g.
But the authors point out that, for comparison, a single 100 g muffin represents about 20% of an average person's total daily energy requirement.
"Physical activity as a weight loss strategy is, therefore, easily foiled by relatively small quantities of excess food," they say.
"Our calculations show that the lungs are the primary excretory organ for fat," they conclude. "Losing weight requires unlocking the carbon stored in fat cells, thus reinforcing that often heard refrain of 'eat less, move more.'"
Source: BMJ 2014; 349
doi: http://dx.doi.org/10.1136/bmj.g7257 (Published online 16 December 2014)
What about diet and exercise?
Study author Rubeen Meerman told
ABC Science,” "If you sit still in a chair and you start breathing more than required, that's hyperventilation and you'll get tingly fingers and palpitations and if you keep going too long you'll faint,"
An average adult will lose around 200 grams of carbon each day at rest.
Meerman tells ABC Science "You can only breathe so many times a day; on a day of rest, you breathe around 12 times a minute so 17,280 times you'll breathe in a day and each one takes 10 milligrams of carbon with it, roughly,"
"So there's your limit on how much you're going to lose in a day with no exercise."