The Obesity Code

Why I'd hand it to you

Jason Fung, a kidney specialist, argues that obesity is driven mainly by hormones, especially insulin, rather than by calories alone. He recommends cutting sugar and refined carbs and using intermittent fasting to bring insulin down. The science is explained in plain terms, and many readers find it a new way to think about weight. Know going in that his insulin-centered model is debated among researchers, who argue calories still matter more than he allows. Fasting also isn't safe for everyone, especially people on diabetes medications. Talk with your doctor before making big changes.

— Matt Jordan