Increased iBAT mass, UCP1 content, and mitochondrial and vascular density found in iBAT from HF/n-3 mice resemble features of cold-induced iBAT activation [16] and are in line with the report of Bargut et al. [23] showing increased thermogenesis in iBAT upon fish oil-based HFD. Here, SLC10A2 is linked to hydrops fetalis.