Association between insulin sensitivity and lean mass loss during weight loss

Objective The study objective was to assess the relationship between insulin sensitivity and changes in total lean mass (LM) and appendicular LM (ALM) during weight loss. Methods Individuals were randomly assigned to either a standard or a moderately reduced carbohydrate diet for 16 weeks. Body composition was assessed using dual‐energy x‐ray absorptiometry and insulin sensitivity index (S I ) using an intravenous glucose tolerance test. Multiple linear regression was used to determine whether baseline S I was predictive of changes in total LM and ALM. Results Participants ( n = 57; baseline BMI 32.1 ± 3.8 kg/m 2 ) lost an average of 6.8 ± 3.2 kg of body weight ( p < 0.001), with 1.5 ± 2.6 kg coming from LM ( p < 0.05) and 0.5 ± 0.73 kg from ALM ( p < 0.05). Multiple regression analysis demonstrated that S I was inversely associated with changes in total LM (kilograms; β = 0.481, p < 0.001), after adjusting for baseline LM, fat mass, acute insulin response to glucose, and weight loss. Similar results were seen when assessing ALM loss (β = 0.359, p < 0.05). Conclusions Identifying individuals with low insulin sensitivity prior to weight loss interventions may allow for a personalized approach aiming at minimizing LM loss.