Even when we’re not working out we burn fat. Whether you’re trying to lose 10 pounds or put on 10 pounds of muscle, fat is a primary source of energy. But rarely do we pause and ask ourselves where it goes. When we’re going through a high-intensity training session, or as we begin to lose those extra winter pounds, how does that fat actually leave the body?
Recently a panel of doctors, dietitians and athletic trainers took a survey on fat loss as part of a study published in the British Medical Journal. More than 50 percent of the experts believed fat is converted to energy and lost as heat. Others thought fat is excreted or turns into muscle.
Australian TV science personality Ruben Meerman joined Andrew Brown, lead researcher and Head of Biotechnology and Biomolecular Science at the University of New South Wales, to use a method where individual atoms of fat being lost could be traced.
Their results “exposed a completely unexpected black hole in the understanding of weight loss amongst the general public and health professions alike,” Brown told the newsroom at UNSW.
Brown and Meerman found that over 80 percent of the fat molecules being “burned off” actually exit the body through exhaling breaths.
For every 10 kg of fat lost, 8.4 kg is exhaled as carbon dioxide. The other 20 percent is lost as water, via urine and sweat.
Breathing out fat makes sense. The harder you work, huffing and puffing during your high intensity workout, the more fat you “burn.” But if the lungs are the primary organs by which we physically lose weight, it begs the question, Can you lose weight simply by breathing more without exercising?
The answer is likely no.
According to Brown and Meerman, for every 10 kg of fat lost, you need to inhale 29 kg of oxygen to break up the fat molecules in the first place and release their energy, water and carbon dioxide. If you consume more oxygen than you need to sustain your resting metabolic rate, you could get really dizzy from the buildup of air, and you might start hyperventilating or pass out.
You breathe heavily during a workout, but the reason you’re burning fat during that workout is because you’re drawing on your fat source, not directly because you’re breathing it out.
If you’re interested in getting a different spin, the folks over at SciShow put together a useful video explaining the findings and breaking it down chemistry-wise. Check it out below.
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