Biological process of fat loss and excretion

When the body undergoes weight loss through a caloric deficit, stored fat is metabolized and converted into other substances. According to data published in the BMJ, the majority of the metabolized fat mass is expelled through the respiratory system.

Specifically, approximately 84% of the original fat mass is converted into carbon dioxide and exhaled through the lungs. The remaining 16% is converted into water, which is then eliminated from the body through natural processes such as sweat and respiration. This process occurs when triglycerides stored in fat cells are broken down into fatty acids and utilized for energy in the presence of oxygen.