To understand the answer, it helps to remember that fat is basically stored energy. Your body converts fat to usable energy for your muscles and other tissues through a series of complex metabolic processes. This causes your fat cells to shrink.
These metabolic activities also generate heat, which helps maintain your body temperature, and waste products. These waste products — water and carbon dioxide — are excreted in your urine and sweat or exhaled from your lungs.
April 21, 2020
- Metabolism. In: Medical Physiology. 3rd ed. Elsevier; 2017. https://www.clinicalkey.com. Accessed March 27, 2020.
- Murphy J, et al. Factors associated with adipocyte size reduction after weight loss interventions for overweight and obesity: A systematic review and meta-regression. Metabolism. 2016; doi:10.1016/j.metabol.2016.09.009.