Despite society’s obsession with weight loss, a study found that most health practitioners have little understanding of what happens to fat when we “lose it.” A team of Australian researchers measured exactly what happens to our fat when we lose weight in 2013 and discovered that doctors’ leading theories are incorrect – we don’t turn our lost mass into heat or energy. We actually exhale it.
Their findings show that 22 pounds (10 kg) of body fat is broken down into 18.5 pounds (8.4 kg) of carbon dioxide, which is exhaled as we breathe, and 3.5 pounds (1.6 kg) of water, which is excreted by urine, tears, sweat, and other bodily fluids.
The majority of the mass is exhaled as carbon dioxide. “It vanishes into thin air,” said Ruben Meerman, a physicist and TV host who was the researcher’s lead author.
Meerman became interested in the biochemistry of weight loss after losing 33 pounds (15 kg) and finding out that no one could tell him where the weight had gone.
After polling 150 doctors, dieticians, and personal trainers, he found that more than half of them believed fat was broken down into heat or energy. Meerman, however, realized as a physicist that this would be in violation of the Law of Conservation of Mass.
Excess carbohydrates and proteins in our diet are transformed into triglycerides (carbon, hydrogen, and oxygen compounds) and deposited in lipid droplets within fat cells, causing us to gain weight. To lose weight, you must break down triglycerides in order to gain access to their carbon.
According to the findings, we need to inhale 64 pounds (29 kg) of oxygen to fully break down 22 pounds (10 kg) of human fat (and somewhere along the way, burn 94,000 calories). This reaction yields 62 pounds (28 kilograms) of CO2 and 24 pounds (11 kilograms) of water.
The team writes in the paper, “Our calculations show that the lungs are the main excretory organ for fat.”
They couldn’t figure out what was happening to the fat cells in this reaction, though. After months of study, Meerman discovered a formula from a 1949 paper that solved the problem. It showed that in fat, oxygen atoms are shared 2:1 between carbon and hydrogen (forming carbon dioxide and water). This led them to the conclusion that 84 percent of the atoms in a fat molecule was exhaled as carbon dioxide, with the remaining 16 percent ending up as water.
Unfortunately, breathing deeply is not enough to loose weight; we must also exercise in order to unlock the carbon and break down the fat.