he's chief executive of a firm called hvmn.way to boost productivity and increase our health span — that is, the number of years you are fully able before the troubles of old age. geoffrey promotes the 36—hour fast that i'm on and his company sells products they claim will boost your body's reaction to fasting. so when you're extending beyond a 24—hour fast, you're dipping into a metabolic state called ketosis which converts your stored body fat into a really efficient source of energy called ketone bodies. as one gets better at being in ketosis, cognitive clarity ends up being a productivity boost. to test it, we measured the ketone level in my body with a simple blood test. my ketone levels were low, as could be expected, but next i drank one of hvmn's ketone—producing products. you can expect to see within 15 minutes equivalent to five, seven days worth of fasting level of ketones in your system. wow. the science behind what benefits can be had isn't exactly watertight. one study suggests one of hvmn's other products may not