You’re not imagining it: There really are differences between the way men and women diet, lose weight and respond to exercise. Some of the differences stem from biology; other differences are behavioral. But though many of these seem to give men a head start, they shouldn’t be taken to imply that guys have it easy. No matter who you are or where you’re starting, the road to your ideal weight is difficult at best, and confusing for most. But the information that researchers are unearthing about the differences in the way that men and women lose weight inspires hope that...