New Hope for Obesity and Diabetes: Humans have 2 types of fat tissue: white fat which stores excess energy in the form of triglycerides, and brown fat, which efficiently dissipates stored energy as heat. While white fat can be “browned” by the use of thiazolidazine drugs (TZD’s), their use results in many adverse side effects including liver toxicity, bone loss, and ironically weight gain. Researchers at Columbia University Medical Center studied sirtuin enzymes, which among other things are believed to affect metabolism. They found that when sirtuin activity increases in mice, so does metabolic activity. The researchers found that sirtuins boost metabolism by promoting the browning of white fat. Sirtiuns work by deacetylation, the severing of chemical bonds between acetyl groups and proteins. They proved that sirtuins remove acetyl groups from ppar-gamma, which is crucial to the browning of fat. Accili D et al. ScienceDaily. 2013 Aug. 2.
Polyphenols such as resveratrol, are thought to act through sirtuins, and SirT1 promotes a state of increased energy efficiency that protects against insulin resistance and hyperglycemia. Banks A et al. SirT1 gain-of–function increases energy efficiency and prevents diabetes in mice. Cell Metabolism. 2008 Oct; 8(4):333-341.