Iron: Iron, too, remains a critical nutrient. Adult women between the ages of 19 and 50 need 18 mg a day. Pregnant women should shoot for 27 mg a day. “The volume of blood almost doubles when women are pregnant, which dramatically increases the demand for iron,” Schwartz tells WebMD. After delivery, lactating women need far less iron, only about 9 mg, because they are no longer menstruating. But as soon as women stop breast-feeding, they should return to 18 mg a day.
Here, too, body size is the main difference between the needs of males and females. Despite all the hype about high-protein diets, our protein requirements are really quite modest — only about a third of a gram per pound of body weight. For a 125-pound woman, that amounts to about 42 grams, for a 175-pound man, 58 grams. That's a tiny difference, just about half an ounce a day.
Even if you are the most independent exerciser around, give a group fitness class a shot at least once a week—you may find that you enjoy it more than sweating solo. “Happiness and health are shared through social connectedness and closeness,” says Greg Chertok, director of sport psychology at the Physical Medicine and Rehabilitation Center in New Jersey. “Geography and proximity are predictors of how contagious emotions can be, and this may translate into an athletic environment too.” Sign up for Bikram, CrossFit, spin, or Zumba, and you could find yourself—gasp!—smiling at the gym thanks to your classmates.
If you thought texting changed your love life, imagine what it could do for your waistline. When people received motivational text messages promoting exercise and healthy behaviors twice a week (i.e., “Keep in the fridge a Ziploc with washed and precut vegetables 4 quick snack. Add 1 string cheese 4 proteins”), they lost an average of about 3 percent of their body weight in 12 weeks. Participants in the Virginia Commonwealth University study also showed an improvement in eating behaviors, exercise, and nutrition self-efficacy, and reported that the texts helped them adopt these new habits. Find health-minded friends and message each other reminders, or program your phone to send yourself healthy eating tips.