**Chap­ter Sum­ma­ry:**

In Chap­ter 5, titled “Eat Less, Live Longer? The Sci­ence of Hunger and Health,” the nar­ra­tive revolves around the dis­cov­ery and poten­tial ben­e­fits of rapamycin, a mol­e­cule with sig­nif­i­cant impli­ca­tions for longevi­ty and health. The chap­ter begins with the author and three friends trav­el­ing to East­er Island, inspired by their quest to explore the ori­gins and impacts of rapamycin, a sub­stance named after the island’s native name, Rapa Nui. Dis­cov­ered in a soil sam­ple by a Cana­di­an team in 1964 and fur­ther inves­ti­gat­ed by Suren Seh­gal in Mon­tre­al, rapamycin was found to have impres­sive antimi­cro­bial prop­er­ties and the poten­tial to extend mam­malian lifes­pan, a dis­cov­ery that stemmed from its abil­i­ty to inhib­it a cel­lu­lar growth path­way.

Rapamycin’s jour­ney from an anti­fun­gal agent to a land­mark drug in trans­plant med­i­cine and can­cer treat­ment show­cas­es its diverse appli­ca­tions, includ­ing its use in pre­vent­ing organ rejec­tion and as a coat­ing for arte­r­i­al stents. The focus then shifts to rapamycin’s remark­able impact on aging and health. Exper­i­ments have shown that rapamycin can sig­nif­i­cant­ly extend the lifes­pan of mice, even when admin­is­tered late in their lives, sug­gest­ing its poten­tial as a longevi­ty-enhanc­ing drug. This dis­cov­ery ties into broad­er themes of caloric restric­tion and its effects on health and lifes­pan, under­ly­ing mech­a­nisms such as the mTOR path­way, and the impli­ca­tions for human health and aging.

David Saba­tini’s work on mTOR high­lights the path­way’s role in bal­anc­ing growth and nutri­ent avail­abil­i­ty, shed­ding light on the genet­ic and mol­e­c­u­lar foun­da­tions of longevi­ty. The chap­ter delves into the prac­tice and prin­ci­ples of caloric restric­tion, trac­ing its his­tor­i­cal roots and sci­en­tif­ic val­i­da­tion as a method to extend lifes­pan in var­i­ous species. Through per­son­al anec­dotes and sci­en­tif­ic explo­ration, the chap­ter explores the com­plex­i­ties of trans­lat­ing these find­ings into human health ben­e­fits, address­ing chal­lenges and promis­ing devel­op­ments in using rapamycin and relat­ed com­pounds to delay aging and enhance healthspan.

Rapamycin’s poten­tial as a longevi­ty drug under­scores the need for fur­ther research, par­tic­u­lar­ly in the con­text of its immune-mod­u­lat­ing effects, which could rede­fine its appli­ca­tions for health, aging, and dis­ease pre­ven­tion in humans. The nar­ra­tive con­cludes with the antic­i­pa­tion of ongo­ing and future stud­ies that could illu­mi­nate rapamycin’s role in pro­mot­ing health­i­er, longer lives, high­light­ing the inter­sec­tions of sci­en­tif­ic dis­cov­ery, med­i­cine, and the quest for under­stand­ing the biol­o­gy of aging.