(CBS) A calorie is a calorie is a calorie.
That basic assumption has long been a core element of Weight Watchers and other weight-loss programs. But under its newly revised "points" system, Weight Watchers is letting dieters know that not all calories are equal.
Under the old system, foods were assigned a point value based mostly on their calorie counts. But now points take into account protein, carbohydrates, and other "macronutrients" as well as calories, according to U.S. News.
What does it mean for people following the program? For one thing, It means that 100-calorie pear is a better choice than 100 calories of potato chips. In fact, the program now allows nearly unlimited amounts of fresh fruits and vegetables.
Why the change? Karen Miller-Kovach, the firm's chief scientific officer, told CBS News that the revised program reflects the latest research on weight loss, which indicates that fresh, minimally processed foods are key.
The change also makes things easier on people trying to lose weight.
"Rather than looking at calories, that is, looking at how much fiber, protein and fat is in food, we are able to put it in the PointsPlus system so you are automatically guided towards foods that support weight loss without thinking a whole lot about it, honestly," Miller-Kovach said. "Calories are important, don't get me wrong. However, where those calories come from has an impact."