The average human can have between 10 to 30 billion fat cells. The amount of fat cells in a person's body is set during adolescence and levels off into adulthood; however, children with obesity have twice as many fat cells as adults compared to a child of average weight. Regardless of weight, you replace about 8 percent of your fat cells each year. Your fat cells shrink when you lose weight because of an energy deficit and your body's release of waste products.
Fat cells, referred to as adipocyte cells, absorb the storage form of fat, called triglycerides. Fat cells are able to store triglycerides when you are in an overfed state and need to store excess energy. Insulin, your energy storage hormone, regulates the flow of triglycerides into your fat cells.
Fat Cells Shrink
If you begin to expend energy, your fat cells can be used as a source. When your body needs to burn energy, two enzymes -- hormone sensitive lipase and adipose glyceride lipase -- break down the triglyceride in the fat cells to help fuel items such as the heart or skeletal muscles. This process of breaking down triglycerides is referred to as lipolysis. Although, you lose triglycerides out of your fat cells in the short term, your fat cells will still be there. The fat cells just shrink as a result of this process. If you overeat in the near future, your fat cells can always expand to their original size and even grow larger.
Loss of Waste Products
The main reason you lose weight is your body's removal waste products. As your body uses triglycerides for energy throughout the body, these processes create waste products such as carbon dioxide and water. You then breathe these items out or excrete them through sweating, urine or bowel movements.
If you are interested in losing weight, the most beneficial change will be to focus on your dietary intake. Choose foods that you enjoy and make you feel full while still causing you to consume fewer calories in general. Great filling choices include whole grains like quinoa and steel-cut oats and other nutrient-dense foods such as nuts, beans, olive oil, lentils, plain yogurt, fish and chicken. Additionally, as you begin your dietary changes, use a calorie-tracking app to help monitor your overall energy balance. Track your weight weekly to see if you need to make changes.