AN ANALYSES OF THE RELATIONSHIP BETWEEN BMI AND CARDIOVASCULAR RISK REVEALS THE NEED FOR FURTHER STUDIES

Obesity is widely recognized as a major modifiable cardiovascular risk factor.  Approximately two-thirds of patients who have had myocardial infarction (MI) have a body-mass index (BMI) above the maximum for normal weight (25 or greater). However, the risk posed by obesity for patients with established coronary artery disease (CAD) has not yet been determined. The authors of this review examined the association between various bodyweight categories (low-weight, normal, overweight, obese and severely obese) in patients with confirmed CAD and other cardiovascular events, cardiovascular mortality and total mortality.

Because BMI is the most common measure of bodyweight in the current literature, it was the determinant used for analyses.  Of the 1,560 articles and abstracts identified, only 54 studies met the criteria for inclusion in the review and only 40 of these had weight groups based on BMI.  Analyses of the 40 studies show:

• A low BMI is strongly associated with an increased long-term risk of total mortality and other cardiovascular events.

• Overweight is consistently associated with less risk of mortality and cardiovascular events.

• Obesity is associated with an increased risk of total mortality only for patients with a history of coronary artery bypass graft.

• Severe obesity is associated with a significantly higher risk for cardiovascular mortality but not for total mortality in patients with CAD.

The authors caution that the inverse association between obesity and death in patients with CAD, or “the obesity paradox,” should be further examined based on a number of variables not yet fully explored.

• BMI values do not allow the distinction between measuring lean muscle mass as opposed to body fat.  Underweight patients often have decreased muscle mass and a restricted ability to exercise.  The positive outcomes for the overweight and slightly obese patients may be reflective of their heightened level of lean muscle mass.

• The low weight and normal weight groups were consistently associated with fewer recognized risk factors and, as a result, were less likely to be prescribed prevention therapies, such as healthful diets and increased exercise.  In fact, patient obesity most likely inspires more aggressive treatment.

• All but one of the studies included in the review relied on a one-time patient weight assessment.  The outcomes were therefore not associated with planned or unplanned bodyweight changes.

• Most of the studies did not take into consideration body fat distribution.  Current research supports the theory that central obesity poses a greater risk for CAD than heightened BMI.

The authors contend that a fundamental question remains whether weight loss, or maintaining normal weight can decrease cardiovascular events in patients with established CAD.  In addition, an alternative method to BMI is needed to characterize individuals who truly have excess body fat.

Citation:
Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies. Romero-Corral A, Montori VM, Somers VK, Korinek J, Thomas RJ, Allison TG, Mookadam F, Lopez-Jiminez F. Lancet. 2006 Aug 19;368(9536):666-78.

To read the abstract, go to Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies.

THE LINK BETWEEN A VEGETARIAN LIFESTYLE AND EATING DISORDERS

As it's practiced around the world, vegetarianism has many aspects, including nutritional, social, behavioral and psychological. A review published in the Israeli journal, Harefuah, explored the prevalence of vegetarianism in the western world. The findings show a direct connection between a vegetarian lifestyle and eating disorders, particularly among teenagers. Despite increased efforts to educate the public about the link between diet and health, eating disorders are on the rise. The authors suggest that a vegetarian diet might be a precursor to eating disorders and increase the risk of developing anorexia nervosa.

Citation:
Diet or Health - the linkage between vegetarianism and anorexia nervosa. Aloufy A, Latzer Y. Harefuah. 2006 July;145(7):526-31,549.

To read the abstract, go to Diet or Health - the linkage between vegetarianism and anorexia nervosa.

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