Reappraisal of the optimal fasting time for insulin tolerance tests in mice

Objective Most studies routinely use overnight or 6 h of fasting before testing metabolic glucose homeostasis in mice. Other studies used empirically shorter fasting times (5%) and significant changes in catabolic gene expression in the liver and skeletal muscle. Conclusion Collectively, these data suggest that 2 h of fasting appears optimal for the assessment of insulin tolerance in mice as this duration minimizes major metabolic stress and weight loss.
Highlights • Fasting in mice induces time-dependent metabolic stress and weight loss. • Fasting promotes profound changes in catabolic gene expression in liver and muscles. • Fasting-induced weight loss is attenuated at thermoneutrality. • Two hours fasting appears to be optimal prior to assessing insulin tolerance in mice.