SIRT1 Regulation in Ageing and Obesity.

•Reduced SIRT1 expression or activity in age and obesity associated diseases.•Regulation of Sirt1 transcription and SIRT1 RNA and protein stability as determinants of lower SIRT1 expression in ageing and obesity.•A decline in NAD levels contributes to low SIRT1 activity in ageing.•Modulation of SIRT1 activity and NAD availability as therapeutic strategies to prevent and ameliorate age and obesity associated disorders.