PRKAA2 and obesity due to melanocortin 4 receptor deficiency: Our results suggest that human umbilical cord mesenchymal stromal cells mitigate diabetes‐ and obesity‐induced muscle atrophy via enhancing AMPK/ULK1‐mediated autophagy through exosomes, with implications of applying hucMSCs or hucMSC‐derived exosomes to treat muscle atrophy.