“Like rapamycin, metformin mimics aspects of calorie restriction. But instead of inhibiting TOR, it limits the metabolic reactions in mitochondria, slowing down the process by which our cellular powerhouses convert macronutrients into energy.20 The result is the activation of AMPK, an enzyme known for its ability to respond to low energy levels and restore the function of mitochondria. It also activates SIRT1, one of my lab’s favorite proteins. Among other beneficial effects, metformin inhibits cancer cell metabolism, increases mitochondrial activity, and removes misfolded proteins.21”