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.
Prepare more of your own meals. Cooking more meals at home can help you take charge of what you’re eating and better monitor exactly what goes into your food. You’ll eat fewer calories and avoid the chemical additives, added sugar, and unhealthy fats of packaged and takeout foods that can leave you feeling tired, bloated, and irritable, and exacerbate symptoms of depression, stress, and anxiety.
"Studies show that omega-3 fatty acids are cardio-protective and the basis for the AHA recommendation to consume fatty fish twice weekly," she says. "But the studies do not show that popping a supplement can have the same benefit in healthy individuals." She adds, "There is also a misperception that fish oils can lower cholesterol, but this is not true."
A well-balanced diet, comprised of a variety of foods, adequately meets women’s needs for vitamins, minerals and energy. For good health, women need to pay special attention to calcium, iron and folate (folic acid) intake. A healthy diet also should minimize the intake of fat and sugar. Diets high in saturated or trans fat can promote high levels of blood cholesterol and increase risk for heart disease. A diet that includes high sugar provides empty calories, or calories that do not provide any nutritional value and often times replace more nutritious food selections.
The European Union's (EU) Food Supplements Directive of 2002 requires that supplements be demonstrated to be safe, both in dosages and in purity. Only those supplements that have been proven to be safe may be sold in the EU without prescription. As a category of food, food supplements cannot be labeled with drug claims but can bear health claims and nutrition claims.
"These products provide a subtle, incremental effect. You can't use a sports supplement for a week and expect to gain pounds of muscle, but if used properly, research shows they can provide a slight, not overwhelming, edge," says Andrew Shoa, PhD, vice president for regulatory affairs for the Council for Responsible Nutrition, a trade association for the dietary supplement industry.
Fats contain both saturated and unsaturated (monounsaturated and polyunsaturated) fatty acids. Saturated fat raises blood cholesterol more than unsaturated fat, which may even help lower harmful cholesterol. Reducing saturated fat (most comes from meat, dairy and bakery products) to less than seven percent of total daily calories may help you reduce your cholesterol level. Whenever possible, replace saturated fat with monounsaturated and polyunsaturated fats.
There's not much doubt about this one: Women need more iron than men, because they lose iron with each menstrual period. After menopause, of course, the gap closes. The RDA of iron for premenopausal women is 18 mg a day, for men 8 mg. Men should avoid excess iron. In the presence of an abnormal gene, it can lead to harmful deposits in various organs (hemochromatosis). Since red meat is the richest dietary source of iron, it's just as well that men don't need to wolf down lots of saturated fat to get a lot of iron.
The tiny gender differences in minerals other than calcium and iron depend on body size. But while the dietary requirements for selenium fit this rule, men may benefit from supplements of about 200 micrograms a day, a level about four times above the RDA. That's because both a clinical trial and an observational study suggest that selenium may reduce the risk of prostate cancer. It's far from proven, but it's something for men to consider.
Fiber is an important part of an overall healthy eating plan. Good sources of fiber include fortified cereal, many whole-grain breads, beans, fruits (especially berries), dark green leafy vegetables, all types of squash, and nuts. Look on the Nutrition Facts label for fiber content in processed foods like cereals and breads. Use the search tool on this USDA page to find the amount of fiber in whole foods like fruits and vegetables.
Our sedate, modern lifestyle reduces the need for energy from food, which implies a lower food intake or obesity. Loren Cordain, PhD, and coworkers have estimated that hunter-gatherers had significantly higher energy needs than the typical modern office worker.  A lower energy intake generally reduces the absolute intake of all nutrients, while the need for some nutrients is not always reduced proportionally with energy intake. Overall this suggests that more exercise along with a more nutritious diet, including supplements of essential nutrients and less carbohydrates, will help to prevent obesity and maintain health.
To assure supplements have sufficient quality, standardization, and safety for public consumption, research efforts have focused on development of reference materials for supplement manufacturing and monitoring. High-dose products have received research attention, especially for emergency situations such as vitamin A deficiency in malnutrition of children, and for women taking folate supplements to reduce the risk of breast cancer.
If you count calories, count fat calories, too. Food labels indicate how many calories come from fat, both in actual grams and in percentages. This helps you assess the percentage of fat in your diet. If the total number of fat calories is 30 percent or more of the total calories you consume in a day, you probably need to cut back. But don't be misled by terms like "lower fat." Ask yourself "lower than what?" and look at the overall percentage of fat calories in the food.
^ Fortmann, SP; Burda, BU; Senger, CA; Lin, JS; Whitlock, EP (Nov 12, 2013). "Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force". Annals of Internal Medicine. 159 (12): 824–834. doi:10.7326/0003-4819-159-12-201312170-00729. PMID 24217421.
Carbohydrates should provide 45%–65% of your daily calories. Most of those calories should come from the complex carbohydrates in high-fiber and unrefined foods, such as bran cereal and other whole-grain products, brown rice, beans and other legumes, and many fruits and vegetables. These carbohydrates are digested and absorbed slowly, so they raise the blood sugar gradually and don't trigger a large release of insulin. People who eat lots of these foods have higher HDL ("good") cholesterol levels and a lower risk of obesity, diabetes, and heart disease. A good amount of soluble fiber in the diet lowers LDL ("bad") cholesterol, and high-fiber diets reduce the risk of intestinal disorders ranging from constipation and diverticulosis to hemorrhoids. Some studies have shown that fiber may help reduce the risk of colon cancer. Men need more fiber than women: 38 vs. 25 grams a day before the age of 50 and 30 vs. 21 grams a day thereafter.