Nature puts a "survival switch" in our bodies to protect us from starvation. Stuck in the "on" position, it's the hidden source of weight gain, heart disease, and many other common health struggles. But you can turn it off.

Dr. Richard Johnson has been on the cutting edge of research into the cause of obesity for more than a decade. His team's discovery of the fructose-poweredsurvival switch-a metabolic pathway that animals in nature turn on and off as needed, but that our modern diet has permanently fixed in the "on" position, where it becomes afat switch-revolutionized the way we think about why we gain weight.

InNature Wants Us to Be Fat, he details the mounting evidence on how this switch is responsible both for excess fat storage and for many of the major diseases endemic to the Western world, including heart disease, cancer, and dementia. Dr. Johnson...