A personalized approach to metabolic aspects of obesity.

Metabolic syndrome, which is entwined in semantic controversy as to its actual existence as a distinct entity, links several important health conditions with obesity, and more specifically, excessive visceral adiposity. The most common linked disease states include type 2 diabetes mellitus, hypertension, dyslipidemia, obstructive sleep apnea, and cardiovascular and coronary heart disease. Much of the controversy surrounding the metabolic syndrome case definition is the purported centrality of insulin resistance as root cause, there being no universally agreed-upon standard for measurement of insulin resistance. Over the past decade, the visceral adipocyte itself has emerged as a key contributor rather than passive bystander in the genesis of the metabolic syndrome. Rather than being a simple storage bin for excess triglyceride, the visceral adipocyte is an active endocrine cell secreting a variety of signal hormones known in the aggregate as adipokines. In optimal health, the predominant recognized adipokine is adiponectin, with downstream insulin-sensitizing, anti-inflammatory, antithrombotic, provasodilatory effects systemically. By contrast, metabolic syndrome is characterized by reduced adiponectin and increased inflammatory adipokine secretion, with downstream effects of insulin resistance, heightened inflammation, prothrombosis, and vasoconstriction. These alternative metabolic states of the adipocyte are characterized in this review as metabolic "yin" and "yang." Lifestyle modifications and drug therapies that promote weight loss, increased physical exercise activity, and increased adiponectin production tend to modulate the system favorably toward metabolic "yin."