Effects of Lifestyle-Based Interventions on Obesity and Related Metabolic Risk Factors with Minimal or No Weight Change
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Background: Recent evidence suggests weight loss is not necessary to reduce obesity related co-morbidities. The principal finding within these reports is based on examination of group mean values. Accordingly, it is possible that within a given group, the subjects who failed to lose weight did not experience any health improvement, a finding masked by the exaggerated improvement in those who did lose weight. We sought to determine whether a gradient exists between the inter-individual change in bodyweight and corresponding changes in body composition and metabolic risk factors in response to minimal or no weight loss. Methods: Total adipose tissue (AT) and skeletal muscle (SM) were determined by magnetic resonance imaging (MRI) in 46 men and 42 women participating in lifestyle-based programs designed to reduce obesity and related metabolic risk factors. Visceral AT (VAT) and abdominal subcutaneous AT (ASAT) were calculated from a single image at the L4-L5 inter-vertebral space. Glucose uptake was calculated using a hyperinsulinemic-euglycemic clamp procedure. Blood pressure (BP) was determined using an electronic cuff or manually using standard procedures. Waist circumference (WC) was taken at the level of the last rib. Results: Bodyweight did not change in men or women (p>0.10). Collapsed across gender, with the exception of ASAT, SM, and systolic BP, all other anthropometric, body composition, and metabolic risk factor measures improved significantly following treatment (p<0.05). With few exceptions, regression analysis revealed that changes in bodyweight or WC were not associated with corresponding changes in body composition measures or metabolic risk factors (p>0.05). To further consider whether a gradient existed between weight change or WC change on body composition and metabolic risk factors, subjects were cross-classified according to their level of weight/waist change (tertiles) and their respective change in either body composition or metabolic risk factor. Neither weight nor WC change tertile was related to any body composition or metabolic risk factor in a gradient fashion (p>0.05). Conclusion: These findings reinforce and extend the observation that independent of gender, lifestyle-based interventions are associated with reductions in obesity and related metabolic risk factors despite minimal or no weight loss.