An old saying posits that the definition of insanity is doing the same thing over and over and expecting different results. If the $60-billion dieting industry is any indication, our society is steps away from a straitjacket. Despite copious evidence that most diets fail in the long term (beyond two years), many people repeatedly attempt to shrink their bodies, and the majority end up heavier than when they started. As Daniel Engber details in this issue, science is no closer to understanding why weight loss from dieting doesn’t stick. What we know so far is that a complicated interplay of factors leads to scale bounceback—from levels of hormones such as the hunger hormone leptin to the shape and size of fat cells and hereditary genetics (see “Unexpected Clues Emerge about Why Diets Fail”).

Elsewhere in this issue, Kendall Powell reports on a new path of research that is harnessing the innate competitive nature of cells with the hope for novel cancer treatments (see “Survival of the Fittest Cells”). And Robin Lloyd investigates harmful emissions from the plastics contained in so-called cured-in-place pipes, which are commonly used in sewer pipe renovation (see “Health Concerns Mount as More Old Sewer Pipes Are Lined with Plastic”). It never fails to surprise me that the science of health and medicine can touch nearly every human industry—from marketing diet shakes to the manufacture of construction materials. If we’re lucky and wise, our discoveries will lead to improved health and welfare for everyone.