Calories do count.  The average American is eating about 400 calories more today than 30 years ago.  That alone explains the obesity epidemic.  As to why, a pretty good reason is loss of hormonal control due to increased inflammation creating hormone resistance including insulin and leptin resistance coupled with more inflammation coming into the body via the gut.  The only way to lose excess body fat (which is far more important than losing weight) is constant calorie restriction without hunger or fatigue.  This is difficult, but can be achieved as the 10,000 people on the National Weight Registry has demonstrated.  To control your hormones involved in energy balance, your primary goal is reducing inflammation so following an anti-inflammatory diet is a good starting point.