Transgenic mice that overexpress SIRT1 partiallyphenocopy CR [13], and areprotected from age-related diseases such as diabetes, osteoporosis, and cancer [14].SIRT1-/- mice do not have a longer lifespan on a CR diet [15].Resveratrol, a polyphenol from grapes, works via the SIRT1 pathway to extendthe lifespan of older mice fed a high-fat diet [16].Similar to resveratrol, small-molecule activators of SIRT1 mimic the beneficialeffects of CR and protect mice against age-related diseases [17, 18]. Here, SIRT1 is linked to osteoporosis.