Increased Body Fat Diminishes Insulin Sensitivity in Young, Non-Obese, Healthy, Women

Abstract

Obesity is commonly assessed by using body mass index (BMI); however scientific evidence suggests that it is the accumulation of body fat and not excess body weight that adversely affects health. PURPOSE: To study the influence of increased body fat on insulin sensitivity in young, non-obese (BMI: 18.5–25.0 kg/m2), healthy women. METHODS: 32 women (age 19–33 yr) were classified into two groups according to their body composition: normal and high body fat groups (NBF and HBF, % body fat <30 and ≥30, respectively). The two groups did not differ in total energy intake, physical activity levels or maximal oxygen consumption and body fat distribution. Body composition was assessed by DXA and insulin sensitivity by the homeostatic model assessment (1/HOMA). RESULTS: The HBF group had significantly lower insulin sensitivity, compared to the NBF group (0.14±0.01 vs. 0.20±0.02, p < 0.05). No significant differences were found in fasting plasma triglycerides, free fatty acids, cholesterol and HDL-cholesterol. Lineal regression analysis revealed that among the blood biochemical parameters assessed; only triglycerides were significantly associated with insulin sensitivity. CONCLUSION: Data suggest that excess body fat, even in young, healthy women with normal BMI, can diminish insulin sensitivity. Furthermore, our data provide evidence that BMI values may not be appropriate for the assessment of obesity in clinical practice.