Magnetic resonance imaging (MRI) uses radiofrequency energy which is absorbed by the patient. This energy is expressed in terms of specific absorption rate (SAR). Here we analyze the EM and thermal effects of increased lean-body-mass proportions with constant body-mass-index (BMI). We use a combination of techniques to achieve morphed expansion of lean-body-mass (LBM muscle) of non-head skeletal muscle tissue in a computational anatomical human body model. Results indicate that LBM may be a worthwhile anatomical descriptor to consider for impact on thermal risk assessment.