Mind & Body

Where Does The Fat Go After You Burn It?

During a particularly difficult spin class, you might wonder where all the weight you're trying to lose is actually going. The answer: You exhale it as carbon dioxide.

Why It Matters

Nearly half of all Americans are trying to lose weight. According to a 2015 Gallup poll, 49% of Americans say they would like to shed pounds. Could understanding how it actually works help the numbers on the scale move? Maybe. And just in case, here goes...

When you burn more calories than you consume, your body has to dip into its fat storage for energy. This is how people burn fat and lose weight. The way your body burns fat is by oxidizing the molecules that make up the triglycerides that fill up fat cells: glycerol and three fatty acids. According to a 2014 study published by the British Medical Journal, most of the fat you burn turns into carbon dioxide and water. The process of burning 22 lbs (10kg) of fat will produce 62 lbs (28 kg) of carbon dioxide. Surprisingly, 84% of fat that is burned turns into carbon dioxide, and the remaining 16% becomes water.

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Why People Should Know

"Considering the soaring overweight and obesity rates and strong interest in this topic, there is surprising ignorance and confusion about the metabolic process of weight loss among the general public and health professionals alike," the authors of that 2014 study wrote. Many people, including general practitioners, dietitians and physical trainers, believe that "fat is converted to energy or heat, which violates the law of conservation of mass," or that fat is simply converted to muscle. But that's not the case. Considering how much time and energy (and money!) is spent on weight loss each year, it's good to know what's actually happening.

One quick, but important, note: This doesn't mean that simply exhaling more will help you drop pounds. (Don't we wish!) Breathing out, in and of itself, doesn't jumpstart fat burning. But, as Rachel Feltman and Sarah Kaplan of the Washington Post explain, "the huffing and puffing that occurs during an intense workout will be full of the sweet spoils of weight loss."

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Key Facts In This Video

  1. When you eat too much protein or carbs, your body converts it and stores it as fat. 00:28

  2. According to a study published by the British Medical Journal, most of the fat you burn turns into carbon dioxide and water. 01:32

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Written by Curiosity Staff March 24, 2016