HSPA5 and obesity due to melanocortin 4 receptor deficiency: These reports contrast with our study and elevated Chop, but diminished Bip and Xbp1s levels in HFD-fed mice, potentially indicating different trajectories and a major influence of exogenous, environmental factors in the etiologies of hepatic inflammation, ER stress and MASLD in mice with stable obesity versus those undergoing weight fluctuations.