Typical white adipocytes are poor in mitochondria and have a low oxidative capacity. Because of this, the contribution of white adipose tissue (WAT) to whole body energy expenditure is considered relatively small. However, there are studies in both humans and rodents documenting a negative association between mitochondrial content in WAT and obesity, as well as examples of nutritional and pharmacological interventions in animals resulting in obesity resistance that associate with increased oxidative capacity in WAT [reviewed in ( 1 )]. Stimulation of mitochondrial biogenesis and oxidative capacity in white adipocytes, when linked to increased energy expenditure in these cells through increased energy uncoupling and/or waste (e.g., futile cycles), emerges therefore as a potential novel target in the control of obesity and its related medical complications ( 1 ).Vitamin A metabolites (i.e., retinoids) modulate the growth and differentiation of a wide range of cells and tissues. Dietary vitamin A and pro-vitamin A are stored as retinyl esters or intracellularly metabolized to retinoic acid (RA), the main active form of vitamin A ( 2 ). There are two isoforms of RA, all-trans -RA (ATRA) and 9-cis -RA, which exert their effects on cell processes through both genomic and nongenomic mechanisms ( 3 ). After the liver, adipose tissue is a major site of vitamin A storage and metabolism, as well as a main target of ATRA action ( 4, 5 ).