According to the old nursery rhyme, little boys and little girls are made of very different things. While you can fault the rhyme for not being factually accurate, it does highlight an interesting point. In some respects, men and women have different nutritional needs, largely due to differences in male and female hormones.
But we don't start out all that differently, nutritionally speaking.
"If you look at the current federal dietary guidelines for kids, there is no difference in nutritional needs for males and females until age 9, " says Elaine Turner, PhD, RD, associate professor in the department of Food Science and Human Nutrition at the University of Florida in Gainesville.
Once we hit puberty, however, she added, everything changes. And women's unique role as the bearers of children tends to drive their special nutritional needs.
Women Need Fewer Calories
"A woman and man of the exact weight and percentage of fat would burn the same amount of calories for the same amount of exercise, " says Sharon B. Spalding, MEd, CSCS, professor of physical education and health at Mary Baldwin College in Staunton, Va. "However men are usually larger with a higher lean weight and will burn more calories."
So women need fewer calories than men in part because they tend to be smaller and have higher fat percentages than men. That means women have to be choosier about what they eat. If you need fewer calories, the calories you take in need to pack a lot of nutritional punch.
In general, women need around 1, 200 calories every day and men need a few hundred calories more. If you exercise you'll need much more depending on how active you are.