Carbs for Weight Loss & Energy
There are two types of carbohydrates: simple and complex. Simple carbohydrates are found in foods such as sugar and milk. Complex carbohydrates are found in the fibers and starches of plant foods. Whole grains and pasta contain complex carbs as do vegetables and legumes. When you eat any kind of carbohydrate, your body extracts a fuel called glucose (blood sugar). When you exercise, your muscles burn the stored glucose.
Because complex carbohydrates are usually lower in fat and higher in nutritional value than simple carbs, they're a better choice for everyone, including walkers like you. Complex carbs also offer healthy amounts of fiber, a substance that encourages weight loss because it's bulky and therefore fills you up quickly, so you'll eat less.
Power-Eating Tip: Go beyond starches. Slightly more than half of your total daily calories—55 to 60 percent—should come from carbohydrates. Of that, only 40 percent should be complex carbohydrates such as potatoes, whole grain breads and pastas, and fruits. The other 60% of carbohydrate calories can come from a variety of sources, including dairy.
"Many athletes fail to realize that carbohydrates also occur in vegetables and dairy products, and thus they consume more starches than they need to," explains Kristine L. Clark, PhD, RD, director of sports nutrition at the Center for Sports Medicine at Pennsylvania State University in State College.
Fat for Endurance & Immunity
Fat is an essential nutrient for good health, vitamin absorption, brain function, and energy. "Just as many athletes overconsume carbohydrates, they underconsume fats," says Clark. In fact, the latest research shows that fat may increase your endurance and boost your immune system.
When researchers had nine female soccer players eat 2.7 ounces of peanuts (or 450 calories from fat) every day for 1 week, the women ran nearly 1 mile longer than when they ate their usual fare. When an extra 450 calories of carbs were substituted, there was no change.
Another team of researchers studied trained runners and found that those who limited fat in their diet to about 17 percent compromised their immune system. When the level of fat was raised to 32 to 41 percent, performance improved without any jeopardy to immunity.
Power-Eating Tip: Don't cut out too much fat. A super-low-fat diet is not recommended for those who work out. Instead, women should maintain a low- to medium-fat diet with 25 percent of their calories coming from fat, mostly in the form of monounsaturated and polyunsaturated fats.
If you're eating a typical 2,000-calorie-a-day diet, you should be consuming up to 56 g of fat, which is about 11 teaspoons, from all food sources, preferably in the form of olive or canola oil, with very little of it in the form of butter or shortening.
Protein for Muscle Strength
"Protein builds and repairs body tissue, which might be damaged during exercise," says Jackie Berning, PhD, RD, assistant professor at the University of Colorado in Colorado Springs and sports dietitian for the Cleveland Indians and the Colorado Rockies. Eating too much protein, however, strains your kidneys as they get it out of your body. Excess protein may also interfere with calcium absorption and make it more difficult to get the recommended 55 to 60 percent of your calories from carbs.
Power-Eating Tip: Avoid protein overload. Regular walkers need just 0.7 g of protein per pound of body weight each day. For a 135-pound woman, that's 95 g of protein: the amount found in 1 cup of yogurt plus 2 cups of soybeans, or a veggie burger and 1/4 pound of chicken.
Calcium for Bone Strength
While weight bearing exercise is important for strong bones, it's only going to build the bones that you are using the most, explains Priscilla Clarkson, PhD, professor of exercise science and Dean of the Commonwealth College at the University of Massachusetts at Amherst. So if you're a walker, your leg bones will be stronger. But your arms and back need protection too. That's where calcium comes in.
Athletic or not, most women don't get enough calcium. When Connie Georgiou, PhD, RD, of Oregon State University in Corvallis, questioned 104 female exercisers about certain foods, nearly one-third rated macaroni and cheese as unhealthy, and more than one-fifth said that 2% milk was bad for them.
"They're overestimating the amount of fat in dairy products and underestimating their calcium needs," says Georgiou.
Calcium-poor diets can lead to stress fractures and osteoporosis and may also be a cause of muscle cramps, since calcium plays an essential role in muscle contraction.
Power-Eating Tip: Have dairy at every meal. Drink a glass of low-fat milk, or eat another source of dairy with every meal, aiming for about 1,000 mg of calcium per day if you're 50 years old or younger or 1,200 mg if you're older.
Water for Performance
Women average 4.7 cups of water-based liquids a day, but you need a minimum of 13 if you exercise, including walking. The extra fluid replaces what you sweat out and removes the body heat that you generate during exercise.
According to Mindy Millard-Stafford, PhD, professor and associate chair, one of the major causes of fatigue during prolonged exercise may be due to dehydration.
Power-Eating Tip: Don't wait until you're thirsty to sip. Exercising blunts your thirst receptors, so make sure you drink before, during, and after exercise--whether you feel thirsty or not. A good rule of thumb is to take in 6 to 8 ounces of fluid every 20 minutes while exercising. To be safe, keep drinking even after your thirst is quenched.
The simplest way to know whether you're getting enough fluids is to check your urine. If you're urinating about every 2 hours, and it's light colored or clear, you're fine. If it's dark or has a strong smell, you need more liquid.
Vitamins and Minerals for Energy
Studies show that female athletes typically consume less than the recommended levels of zinc and B-complex vitamins such as thiamin, riboflavin, niacin, folate, and vitamins B6 and B12. What's more, iron deficiency, which can lead to fatigue, is one of their most prevalent nutritional deficiencies. And women who are limiting their food intake in an effort to lose weight are even more likely to be deficient in some key nutrients.
Power-Eating Tip: Take supplements, and eat healthier. To keep your energy levels high, you need to make sure you're getting all of the nutrients your body needs. While eating a healthy, balanced diet high in fruits, vegetables, and calcium-rich foods will help ensure this, it's wise to take a daily multivitamin/mineral supplement.
Also, since it's not always easy to get all the calcium you need, take a 500-mg calcium supplement. Here are a few more nutrients that deserve some special attention:
B vitamins: Even sporadic exercise increases your need for the B vitamin riboflavin, and vitamin B6 is involved in metabolizing protein, which your body needs for repairing muscle. What's more, though the Daily Value for vitamin B6 is 1.3 mg, exercise stresses the metabolic pathways that use this vitamin, so athletes and active women may need up to two times the Daily Value.
Good food sources for B vitamins include: chicken breast, acorn squash, watermelon, banana, tomato juice, spinach, broccoli, and rice.
Iron: Iron is essential to the production of red blood cells and plays a vital role in transporting and helping the body use oxygen. It's estimated that about 16% of all American women are iron depleted: not bad enough to be considered anemic, but still low enough to affect physical performance. The Daily Value for iron is 18 mg.
Never take iron supplements unless under the direction of your doctor. Iron can be found in: lean red meats, poultry, eggs, legumes, Cream of Wheat cereal, baked potatoes, soybeans, and clams.
Zinc: Think of zinc as the FedEx of the blood system. It's a zinc-containing enzyme in red blood cells (carbonic anhydrase) that helps the cells pick up carbon dioxide in the body and drop it off in the lungs for exhaling. Without it, our muscles couldn't contract and produce energy. Even slightly reduced levels of zinc can make you feel sluggish.
The more fit you are, the more important zinc is to proper functioning because your body uses more carbonic anhydrase when you're working out than when you're resting. Women need at least 8 mg of zinc a day.
Oysters, lean ground beef, sirloin steak, turkey thighs and drumsticks, and lentil soup are all good food sources of zinc.