Every evening and morning I weigh myself. In the morning I am exactly 2 pounds lighter than the night before. The only explanation I had for my weight loss was I expending energy by tossing and turning while I slept.
Turns out I don’t toss and turn . . . I breathe.
And turns out I’m not alone in my ignorance: 150 doctors, dietitians and personal trainers surveyed shared this surprising gap in their health literacy. “Some thought fat turns into muscle, which is impossible, and others assumed it escapes via the colon. Only three of our respondents gave the right answer, which means 98% of the health professionals in our survey could not explain how weight loss works.”
“The most common misconception by far, was that fat is converted to energy. The problem with this theory is that it violates the law of conservation of matter, which all chemical reactions obey.”
So if not energy, muscles or the loo, where does my fat go every night?
The enlightening facts about fat metabolism
“The correct answer is that fat is converted to carbon dioxide and water. You exhale the carbon dioxide and the water mixes into your circulation until it’s lost as urine or sweat.”
“If you lose 10 pounds of fat, precisely 8.4 pounds comes out through your lungs and the remaining 1.6 pounds turns into water. In other words, nearly all the weight we lose is exhaled.”
“This surprises just about everyone, but actually, almost everything we eat comes back out via the lungs. Every carbohydrate you digest and nearly all the fats are converted to carbon dioxide and water. The same goes for alcohol.
Protein shares the same fate, except for the small part that turns into urea and other solids, which you excrete as urine.”
“The only thing in food that makes it to your colon undigested and intact is dietary fibre (think corn). Everything else you swallow is absorbed into your bloodstream and organs and, after that, it’s not going anywhere until you’ve vaporized it.”
Kilograms in versus kilograms out
“We all learn that “energy in equals energy out” in high school. But energy is a notoriously confusing concept, even among health professionals and scientists who study obesity.”
“The good news is that you exhale 200 grams (7 ounces) of carbon dioxide while you’re fast asleep every night, so you’ve already breathed out a quarter of your daily target before you even step out of bed.”
Eat less, exhale more
If my fat turns into carbon dioxide, could breathing more make me lose weight?
“Unfortunately not. Huffing and puffing more than you need to is called hyperventilation and will only make you dizzy, or possibly faint. The only way you can consciously increase the amount of carbon dioxide your body is producing is by moving your muscles.”