Figure 1.

Autophagy is required to sustain circulating nutrients during fasting, critical for the survival of adult mice. (A) Mammalian survival during fasting requires autophagy. Treatment with tamoxifen (TAM) leads to conditional whole-body deletion of Atg7 in adult Ub-CreERT2^+/−;Atg7^flox/flox mice. While autophagy-proficient hosts can survive during fasting, autophagy-deficient hosts die from hypoglycemia when fasted (Karsli-Uzunbas et al. 2014). (B) Autophagy is essential to sustain circulating nutrients during fasting. Fasting autophagy-deficient hosts leads to the loss of WAT, glycogen in the liver, and proteins in muscle (cachexia) and the failure to maintain circulating glucose.