Many dietitians and personal instructors think that when you burn fat throughout a workout, the body fat is being transformed into fuel for force or energy.

But where does the by-product or waste of this metabolic reaction go?

It’s kinda like this when your body breaks up the molecules that make up your fat cells in your body, the current atoms don’t just stop to exist.

According to Ruben Meerman, a physicist, and Andrew Brown, a biochemist specializing in lipids, their estimates show that weight loss happens via breathing.

Where Does Your Body Fat Go?

As explained by Medical News Today,

“Excess dietary carbohydrates and protein are converted to a type of fat called triglyceride. When people attempt to lose weight, they are attempting to metabolize these triglycerides while keeping their fat-free mass intact…

Triglycerides are comprised of three types of atoms: carbon, hydrogen, and oxygen. Triglyceride molecules can be broken down only by unlocking these atoms, through a process known as oxidation.

The researchers chose to follow the path of these atoms when leaving the body. They found that when 10 kg of fat were oxidized, 8.4 kg were converted and excreted as carbon dioxide (CO2) via the lungs, and 1.6 kg became water (H20).


In order for 10 kg of human fat to be oxidized, the researchers calculated that 29 kg of oxygen must be inhaled. Oxidation then produces a total of 28 kg of CO2 and 11 kg of H20.”