Is visceral obesity a physiological adaptation to stress?

Visceral obesity represents an important risk factor associated with hypertension, diabetes and cardiovascular diseases. Since this condition is associated with a disruption of the functioning of the HPA axis, stress-induced HPA axis activation has been identified to play an important role in this preferential body fat accumulation. HPA axis activation increases cortisol (corticosterone) production which has been shown to exert hyperphagic and antithermogenic effects. Since abdominal adipose tissue has more cells per mass units, higher blood flow and more glucocorticoid receptors, glucocorticoids affect abdominal fat to a greater extent than subcutaneous adipose tissue. Cushing's syndrome in humans is the best evidence showing a link between hypercortisolemia and accumulation of central fat. The Hervey's hypothesis which suggests that fat cells take up and catabolize glucocorticoids is one of the possible regulatory effect that supports the adaptive role of visceral fat in response to stress. This is also supported by other evidence showing that abdominal obesity is associated with an increased cortisol clearance. Hormonal and enzymatic changes have been implicated in this preferential body fat accumulation in response to stress. Specific genetic background may also accentuate this visceral fat accumulation in some individuals exposed to stress. Alternatively, obesity could also be a source of stress promoting the visceral fat accumulation since visceral fat is able to release cytokines which stimulate the HPA axis. Even if the available literature does not permit to establish clearly which comes first, it suggests that visceral obesity could represent a non optimal physiological adaptation to stress. In this context, visceral obesity treatment should focus on stress management and weight loss strategies in order to stop this vicious circle.