During basal respiration supported by complex I and complex II substrates, activated B cell mitochondria from mice with obesity displayed an elevated rate of H2O2 (JH2O2) emission (Figure 2A), which reflects the balance between the amount produced and the amount reduced to water via the thioredoxin and glutathione redox buffering circuits. Here, TXN is linked to obesity due to melanocortin 4 receptor deficiency.