Metabolic Syndrome in Normal-Weight Americans: A New Definition of..

Article Summary

Metabolic Syndrome in Normal-Weight Americans: A New Definition of the Metabolically Obese, Normal-Weight Individual.

St-Onge MP, Janssen I, Heymsfield SB. Diabetes Care. 2004;27:2222-2228.

Objective: To examine the prevalence of metabolic syndrome, including the components of hypertension, diabetes, and dyslipidemia, in a representative sample of the US population, specifically as it relates to patients with normal BMI and in patients who are slightly overweight.

Methods: A total of 7602 subjects who had participated in the Third National Health and Nutrition Examination Survey (NHANES III, N=33,199) were retained for analysis in the current study. Participants were classified as having metabolic syndrome if 3 or more components were present: triglycerides >1.7 mmol/L; HDL cholesterol <1.0 mmol/L (men), <1.3 mmol/L (women); average of 3 blood pressure measurements of >130/85 mm Hg; 6-hour fasting glucose >6.1 mmol/L, waist circumference >102 cm (men) >88 cm (women). Confounding variables assessed by questionnaire included age, ethnicity, education level, economic status, dietary intake, physical activity, and alcohol consumption. Individuals of normal weight were subdivided into 3 BMI groups.

Results: Including all BMI categories, the overall prevalence of the metabolic syndrome ranged from 17.5% in black men to 30.6% in Hispanic women. The least prevalent component of the metabolic syndrome in all sex and ethnic groups was elevated blood glucose concentrations (12%). The prevalence of high triglycerides increased with each increase in BMI in all sex and ethnic groups (P <0.01). Prevalence of low HDL cholesterol increased with increasing BMI, rising to 41.9% in all individuals with a BMI of 25.0 to 26.9 kg/m2. Prevalence of high blood pressure ranked from 6.6% in Hispanic men (BMI 18.5 to 20.9 kg/m2) to 41.5% in non-Hispanic black men in the cohort with the highest BMI.

Conclusion: People in the upper ranges of BMI are more likely to have metabolic syndrome than are those in the lower ranges of BMI (18.5 to 20.9 kg/m²). This suggests that current recommendations supporting weight loss should be modified.