Response to Comment on: Kaiyala et al. (2010) Identification of Body Fat Mass as a Major Determinant of Metabolic Rate in Mice. Diabetes;59:1657–1666

  1. Michael W. Schwartz2,3
  1. 1Department of Dental Public Health Sciences, School of Dentistry, University of Washington, Seattle, Washington;
  2. 2Diabetes and Obesity Center of Excellence, University of Washington, Seattle, Washington;
  3. 3Division of Endocrinology, Metabolism and Nutrition, School of Medicine, University of Washington, Seattle, Washington;
  4. 4Department of Biostatistics, University of Washington, Seattle, Washington.
  1. Corresponding author: Karl J. Kaiyala, kkaiyala{at}

We thank MacLean (1) for his insightful comments regarding both the need to present unadjusted energy expenditure (EE) data and the issue of model selection for EE normalization.

We agree with the recommendation to present unadjusted EE data as part of the analysis—indeed, this standard should be widely adopted in metabolic research. The question of whether to adjust EE for only the best estimate of “metabolic mass,” e.g., lean body mass (LBM), is complex and raises issues of both theoretical and practical importance.

From a theoretical perspective, MacLean notes that when a genetic or other intervention influences EE by altering …

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