Central nervous system controls of adipose tissue apoptosis

Background Increased adipose tissue mass is a common denominator in both obesity and osteoporosis. Obesity is characterized by increased fat storage in subcutaneous and visceral adipose depots resulting from an imbalance between energy intake and energy expenditure, whereas osteoporosis is associated with increased adipocyte production in bone marrow and is not necessarily associated with increased overall adiposity. In obesity a reduction of adipose tissue mass is accompanied by amelioration of the pathophysiological effects. There are currently no therapies that specifically reduce bone marrow adipocyte populations. However, bone formation decreases with increasing proportion of marrow adipocytes (Verma et al., 2002); thus, it is likely that reversal or prevention of bone marrow adiposity may improve bone quality. In the USA, the prevalence of overweight among adults increased by 61% from 1991 to 2000; currently, more than half of all adults are considered overweight and approximately 20% are extremely overweight or obese (Flegal et al., 1998). Obesity is not just a cosmetic problem – there is much evidence indicating that higher levels of body fat are associated with an increased risk for the development of numerous adverse health consequences (Visscher & Seidell, 2001). There is also a tremendous economic burden associated with the recent rise in prevalence of obesity. The economic costs of obesity are estimated to be ∼7% of total healthcare costs in the USA (Colditz, 1999).