Peter M. Janiszewski; Travis J. Saunders; Robert Ross
Posted: 04/14/2008; Am J Lifestyle Med. 2008;2(2):99-108. © 2008 Sage Publications, Inc.
Abstract and Introduction
The metabolic syndrome is a clustering of metabolic risk factors including abdominal obesity,dysfunctional glucose metabolism, dyslipidemia, and elevated blood pressure. Approximately 1 in 4 Americans currently has the metabolic syndrome and are thus at an elevated risk of cardiovascular disease, type 2 diabetes, and mortality. Leading health authorities recommend lifestyle modification consisting of exercise and caloric restriction for treatment and prevention of the metabolic syndrome. Thepurpose of this report is to review the evidence that considers lifestyle modification as a treatment strategy for the metabolic syndrome. The influence of lifestyle modification on abdominal obesity, dysfunctional glucose metabolism, dyslipidemia, and elevated blood pressure is considered. Findings suggest that interventions consisting of exercise and/or caloric restriction are associated withimprovement in all components of the metabolic syndrome, although the magnitude of this effect varies according to the specific component studied and additional factors such as baseline values. The evidence presented supports the promotion of lifestyle modification as an efficacious strategy for the treatment of the metabolic syndrome.
The notion of a common clustering of metabolic riskfactors, now clinically recognized as the metabolic syndrome, was described as early as 1923. However, it was not until Reaven's 1988 Banting lecture that the constellation of insulin resistance, dyslipidemia, and hypertension was first recognized as a unique clinical entity. The seminal observations of Vague and others[4,5] regarding central body fat distribution and disease risk led tothe subsequent inclusion of abdominal obesity as an additional component of the syndrome. Although the pathogenesis of the metabolic syndrome remains elusive, both insulin resistance and abdominal, specifically visceral, adiposity have been proposed as causative factors in the development of the condition.
Various organizations, including the World Health Organization (WHO), theNational Cholesterol Education Program, the International Diabetes Federation, and others,[11-13] have developed unique definitions of the metabolic syndrome. Although the criteria and precise threshold values identifying the metabolic syndrome vary between organizations, they agree on 4 fundamental components: abdominal obesity, dysfunctional glucose metabolism, dyslipidemia, and elevatedblood pressure.[8-13]
Although the prevalence of the metabolic syndrome is largely definition dependent, according to National Cholesterol Education Program criteria, the metabolic syndrome is estimated to affect approximately a quarter of the US population and is particularly prevalent among older adults. Given that the metabolic syndrome is strongly associated with risk of cardiovasculardisease, type 2 diabetes, and mortality, strategies for the prevention and treatment of the condition are needed. Leading health organizations[9,10,13,19] recommend lifestyle modification as the primary treatment strategy for the metabolic syndrome. Specifically, these guidelines target the reduction of total and abdominal obesity levels through increased physical activity and caloricrestriction.[10,13] The purpose of the present review is to elucidate the effects of physical activity and caloric restriction on the major components of the metabolic syndrome: abdominal obesity, dysfunctional glucose metabolism, dyslipidemia, and elevated blood pressure. Alterations in dietary composition, which have also been suggested in the management of the metabolic syndrome,[9,10,13] have...