Excess body fat has been historically viewed as merely a storage depot of excess energy, due to overeating. We now know that adipose tissue consist of both fat cells and immune cells, which live in an anti-inflammatory state when we have a normal waist/hip ratio and are lean. All this changes with obesity. Both the fat and immune cells undergo a remodeling process, wherein each cell type expresses a pro-inflammatory state, which adds to the promotion of a systemic inflammatory state. This transformation has been associated with the expression of chronic disease, such as diabetes, cancer, and heart disease, but also more common conditions like musculoskeletal pain and depression.