The nicotinamide adenine dinucleotide (NAD(+))-dependent protein deacetylase SIRT1 has been linked to fatty acid metabolism via suppression of peroxysome proliferator-activated receptor gamma (PPAR-gamma) and to inflammatory processes by deacetylating the transcription factor NF-kappaB. First, modulation of SIRT1 activity affects lipid accumulation in adipocytes, which has an impact on the etiology of a variety of human metabolic diseases such as obesity and insulin-resistant diabetes. Second, activation of SIRT1 suppresses inflammation via regulation of cytokine expression. Using high-throughput screening, the authors identified compounds with SIRT1 activating and inhibiting potential. The biological activity of these SIRT1-modulating compounds was confirmed in cell-based assays using mouse adipocytes, as well as human THP-1 monocytes. SIRT1 activators were found to be potent lipolytic agents, reducing the overall lipid content of fully differentiated NIH L1 adipocytes. In addition, the same compounds have anti-inflammatory properties, as became evident by the reduction of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). In contrast, a SIRT1 inhibitory compound showed a stimulatory activity on the differentiation of adipocytes, a feature often linked to insulin sensitization.