Instead of using the controversial body mass index, or BMI, to assess weight, an international group of scientists proposes an approach that looks at how excess body fat affects health

Habits like getting adequate exercise, nutrition, and sleep can have profoundly positive effects on overall health whether they affect weight or not, Erlanger says. A recent research review, for example, found that cardiorespiratory fitness is a better predictor of longevity than weight.

When the issue is obesity, the questions are many, and the routes to answers anything but straight. What is abundantly clear is a need for consensus on two foundational matters: What is a useful definition for obesity?