I subscribed to this in MY early 20's way back in the magazines infancy. Back when the cover photo's were black and white and most of the cover "models" were female athletes. It's changed since then, catering a little more to the "Cosmo" crowd. Which is fine, just not for me. It just doesn't feel like it applies as much to someone in their thirties married with kids as someone in their twenties who apparently has the money and lack of self-control to spend $90 on a designer t-shirt (really).
Young adults. Teen girls and young women usually need more calories than when they were younger, to support their growing and developing bodies. After about age 25, a woman’s resting metabolism (the number of calories her body needs to sustain itself at rest) goes down. To maintain a healthy weight after age 25, women need to gradually reduce their calories and increase their physical activity.