Iron: Essential for healthy blood cells, iron becomes especially important when girls begin to menstruate. With each period, a woman loses small amounts of iron. “About 10% of American women are iron deficient,” says Dorothy Klimis-Zacas, PhD, a professor of nutrition at the University of Maine and co-editor of Nutritional Concerns of Women (CRC Press, 2003). “About 5% have iron deficiency anemia.” Symptoms of low iron include fatigue, impaired immunity, and poor performance at school or work.
If you usually head to the gym after work, take heed: Mental exhaustion can make you feel physically exhausted, even when you have plenty of energy, reports a Medicine & Science in Sports & Exercise study. When people played a brain-draining computer game before exercising, they reported a subsequent workout as being harder, yet their muscles showed the same activity as they did doing the same workout after an easy mental game. So if you think you can’t eke out those last 10 minutes on the rowing machine, remember: You can! [Tweet this motivation!]
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.