This week Reactions tackles the diet fad that never dies--low carb. There's a lot of science that goes on with the keto diet and cutting out carbohydrates. Low-carb diets were a thing in the late 90s and they’re still a thing now. But why does this fad have staying power? Is it because the touted benefits are real? Or is that greasy, low-carb burger fried in snake oil?