This is a series of four different paintings showing fat cells, called adipocytes in obese individuals and how they lose their size with regular exercise. Note the size of the fat cell shrinks with decreasing weight, but the number of fat cells do not. I have put a silhouette on each figure to show how increasing activity decreases weight, and changes size of fat cells.
I also show macrophages in white and purple. Note the white macrophages are more prominent with increased fat and the dark purple cells are more prominent in the normal weight individual that is running. These two types of macrophages have different functions. The white ones, called M1s, release chemicals, called cytokines, that produce inflammation and pain. The purple ones, called M2s, release chemicals that reduce inflammation and are analgesic. Regular exercise can change these macrophage types to increase the chemicals that reduce pain and inflammation.
Obesity is associated with a number of other diseases including chronic pain, heat disease and diabetes. Systemic inflammation contributes to these conditions, and regular exercise is an effective treatment for these conditions.