Many people say you burn it off- it goes poof. That is problematic as it violates at least one law of physics (energy is not created nor destroyed). You breath most of it out as CO2 and eliminate some via sweating and during your bathroom breaks.
What Happens to Fat When You Lose Weight?
Ever wonder what really happens to fat during your fat loss phases? Read this article to learn more about the science behind fat loss and what happens!
We all know that adhering to a caloric deficit will result in weight loss. “Eat less, move more,” and your weight will eventually drop.
But have you ever wondered what actually happens to fat when you lose weight? Many people think fat leaves the body as energy or heat, while others think it turns to muscle or gets pooped out1.
As you might know, energy is stored as triglycerides (i.e. fat) in our fat cells. These cells that specialize in fat storage are called adipocytes. Research suggests that the number of fat cells that we have is largely set during childhood2.
If we gain weight, we can increase the number of fat cells throughout adulthood. However, we can’t get rid of the fat cells we already have. (The only way to get rid of fat cells is to have them removed via a procedure such as liposuction.)
So, if the fat cells don’t disappear when we “lose fat,” then what happens to them?
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What Happens to the Fat?
Where does the fat go after it is broken down to be used as energy? Triglycerides and their fatty acid and glycerol components are made up of carbon, hydrogen, and oxygen. The oxidation of triglyceride results in carbon dioxide, water, and energy. The reaction for the oxidation of a single triglyceride molecule can be summarized as:
C55H104O6 + 78O2 → 55CO2 + 52H2O + energy1Thus, after fat is broken down, it leaves the body as carbon dioxide and water. Most of it is exhaled as carbon dioxide. The rest leaves the body as water through urine, sweat, or other bodily fluids. Approximately 84% turns into carbon dioxide, and 16% turns into water1. This means that most fat is “lost” through the lungs!
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