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As you grow older, you may need fewer calories, particularly if you are less active than when you were younger, says the National Institute on Aging (NIA). But you still need nutrients for good health. And you need more of certain nutrients, such as vitamin B12, calcium, and vitamin D.

Older adults and younger adults alike should limit how much saturated fat they eat. Saturated fat is found in whole-fat dairy products and meat. The USDA's Dietary Guidelines for Americans says that no more than 30 percent of your daily calories should come from fat. Only 10 percent of the fat you eat should be saturated fat. Too much saturated fat has been linked to heart disease.

A healthy diet balances the calories you eat with the calories you use. In this way, you can reach or maintain a healthy weight. If you need 2,000 calories a day, you should eat: six to 11 servings of grains (three servings should be whole grains); 2-1/2 cups of vegetables and two cups of fruit; three cups of nonfat or low-fat milk, cheese, or yogurt; two to three servings of meat, poultry, fish, beans, eggs, or nuts.

If you are counting calories, it's important to watch your servings. Food makers put serving sizes and calories per serving on the nutrition label.

Foods often taste different to an older adult because aging can affect the senses of taste and smell, the NIA says. It may be more difficult to tell when a food is no longer fresh. To help avoid problems with spoiled food, you can date foods that you put in the refrigerator. Medicines also can affect the way foods taste.

You still need to drink enough water and other beverages each day for good health. That's usually eight eight-ounce glasses of fluid. Talk with your doctor if you have incontinence to see what can be done without cutting back on your fluid intake. Getting enough fluid can be a problem for older adults, because they may not be able to tell as easily when they are thirsty. If you are drinking enough fluids, your urine will be pale yellow, the NIA says. If it is a bright or dark yellow, that means you need to drink more liquids.

Fiber may prevent constipation and conditions that affect digestion, the NIA says. It may also lower cholesterol and blood sugar and help you have regular bowel movements. Fiber is found in fruits, vegetables, beans, nuts, seeds, brown rice, and whole grains, such as oat, barley, wheat, corn, and rice bran. It is the part of plant foods that your body cannot digest. To add more fiber to your diet, leave the skins on fruits and vegetables, use whole-grain foods, and choose whole fruit over fruit juice.

Other ways to cut food costs, according to the NIA: Plan your meals around foods that are on sale. When you cook, make extra of a particular dish, then refrigerate it to use within a day or two or freeze it in containers that have only as much as you would eat for one meal and use within a month or two. If you have a friend who is willing, share the cost of meals—and the preparation—with that person. You can check with your local agency on aging to see if you may be eligible for food stamps. Community centers or churches may offer free or inexpensive meals for older adults. If you are eligible consider Meals-On-Wheels.

You need more of these vitamins as you age, the Academy of Nutrition and Dietetics says. This is especially true if you are a vegetarian. Sources of vitamin D include fortified dairy products and fortified cereals, as well as the sun. If you do not eat dairy products, and do not get out in the sun, you may need a vitamin D supplement. Vitamin B12 is found only in animal foods such as meat, milk, and eggs. As you age, you are less able to absorb this vitamin, so you might need a supplement.