For over a century, fasting regimens have improved health, lifespan and tissue regeneration in diverse organisms, including humans^1,2,3,4,5,6. However, how fasting and post-fast refeeding affect adult stem cells and tumour formation has yet to be explored in depth. Here we demonstrate that post-fast refeeding increases intestinal stem cell (ISC) proliferation and tumour formation; post-fast refeeding augments the regenerative capacity of Lgr5⁺ ISCs, and loss of the tumour suppressor gene Apc in post-fast-refed ISCs leads to a higher tumour incidence in the small intestine and colon than in the fasted or ad libitum-fed states, demonstrating that post-fast refeeding is a distinct state. Mechanistically, we discovered that robust mTORC1 induction in post-fast-refed ISCs increases protein synthesis via polyamine metabolism to drive these changes, as inhibition of mTORC1, polyamine metabolite production or protein synthesis abrogates the regenerative or tumorigenic effects of post-fast refeeding. Given our findings, fast–refeeding cycles must be carefully considered and tested when planning diet-based strategies for regeneration without increasing cancer risk, as post-fast refeeding leads to a burst in stem-cell-driven regeneration and tumorigenicity.

一个多世纪以来，禁食疗法改善了包括人类在内的多种生物体的健康、寿命和组织再生^1,2,3,4,5,6 。然而，禁食和禁食后重新进食如何影响成体干细胞和肿瘤形成仍有待深入探讨。在这里，我们证明禁食后重新喂养会增加肠道干细胞（ISC）增殖和肿瘤形成；禁食后恢复增强了Lgr 5 ⁺ ISC 的再生能力，并且禁食后 ISC 中肿瘤抑制基因Apc的缺失导致小肠和结肠中的肿瘤发生率高于禁食或随意喂养的情况状态，表明禁食后重新进食是一种独特的状态。从机制上讲，我们发现禁食后 ISC 中 mTORC1 的强烈诱导会通过多胺代谢增加蛋白质合成，从而驱动这些变化，因为抑制 mTORC1、多胺代谢物产生或蛋白质合成会消除禁食后重新喂养的再生或致瘤作用。鉴于我们的发现，在规划基于饮食的再生策略时必须仔细考虑和测试快速再喂养周期，而不增加癌症风险，因为快速再喂养后会导致干细胞驱动的再生和致瘤性的爆发。