Who doesn’t love french fries? We get it… BUT… A McDonald’s french fry has a half-life of 51 days in your body. FIFTY ONE. You eat it once, and it’s still circulating in your system a month and a half later. Have it multiple times a year and your bloodstream never actually clears it. Nobody’s telling you to never eat a fry again. But this is the stuff nobody thinks to tell you, and it adds up faster than most people realize.