Role Of Insulin Sensitivity In Lean Mass Changes During Weight Loss With Monitored Exercise

Title: Role of Insulin Sensitivity in Lean Mass Changes During Weight Loss with Monitored Exercise Given the high prevalence of obesity and associated comorbidities, weight loss is often sought out by clinicians. However, weight loss from non-fat tissue makes up 20% to 30% of the weight lost in individuals with obesity. Lean mass (LM) plays an essential role in physical function and metabolic health, and low lean mass is associated with greater mortality. Thus, it is important to understand how to minimize loss of lean mass during weight loss. PURPOSE: To determine whether baseline insulin sensitivity is associated with total and appendicular lean mass loss during weight loss in the presence or absence of aerobic or resistance exercise. METHODS: A secondary analysis was conducted using data from a weight loss study in adult women. Duration of the intervention was the length of time required for the individual to reach a body mass index (BMI) < 25 kg.m2 (~21 weeks). Following baseline testing, women were randomized to one of three groups: diet only, diet plus aerobic exercise, or diet plus resistance exercise. Supervised exercise occurred 3x per week. All food was provided during the intervention. Body composition was assessed using dual-energy x-ray absorptiometry (DXA). Baseline insulin sensitivity was measured using an intravenous glucose tolerance test and minimal modeling to derive the insulin sensitivity index (SI) and the acute insulin response to glucose (AIRg). RESULTS: Multiple linear regression analyses showed the group*SI interaction was significantly associated with changes in total LM (β = .474, p = 0.003) after adjusting for race, group, total weight loss, baseline FM, baseline LM, baseline AIRg and baseline SI (adjusted r2 = 0.371). Similarly, the group*SI interaction was significantly associated with changes in appendicular LM (ALM) (β = 0 .462, p = 0.009) after adjusting for race, group, total weight loss, baseline ALM, baseline AIRg and baseline SI (adjusted r2 = 0.231). CONCLUSION: Greater baseline insulin sensitivity was associated with less loss of total and appendicular LM during weight loss. Supported by: R01DK049779