A healthy diet and lifestyle are your best weapons against age-related diseases.

A healthy diet and lifestyle are your best weapons against age-related diseases.Watch: The Best Anti-Aging Foods

Aging is inevitable. The so-called fountain of youth? Sadly, just a beautiful fantasy. Still, you can exert some control over your decade-by-decade destiny. By following a healthy lifestyle-that is, eating a nutrient-packed diet and staying active throughout life (or starting right now)-you can help slow the aging process and perhaps even stave off age-related chronic diseases, including osteoporosis, diabetes and heart disease. While basic nutrition needs remain pretty constant throughout life, requirements for specific nutrients may increase-or decrease-slightly as you get older. Also, as we age, caloric needs drop, making it ever more important to pack your diet with the good stuff-vegetables, fruits and whole grains, for example-and limit less-healthy treats. The nutrition experts at EatingWell recommend the following eating tips for healthy aging.

Pack your diet with plant-based foods.

Fruits, vegetables, whole grains and other plant-based foods are rich sources of phytochemicals, beneficial compounds that may help protect against age-related conditions like heart disease, high blood pressure and macular degeneration, a leading cause of blindness in older people. Fill at least two-thirds of your plate with vegetables, fruits, whole grains and beans and the remaining one-third or less with lower-fat sources of protein, like fish, poultry or lean meat. Choose vegetables and fruits that represent a rainbow of colors: dark leafy greens (e.g., kale and spinach), deep yellow and orange vegetables (e.g., corn and sweet potatoes), tomatoes and other red foods (e.g., bell peppers, strawberries) and blue and purple powerhouses like blueberries and purple grapes.

Keep weight in check.

As you get older, your body loses lean body mass (muscle) and your metabolism, or the rate at which you burn calories, slows. Bottom line: Through the years, you'll need fewer calories to maintain a healthy weight. Stay within a healthy range by filling up on lower-calorie nutrient-packed foods-particularly vegetables and fruits-and cut back on foods that contain a lot of fat or added sugars. Carrying around extra pounds can increase your chances of developing heart disease, diabetes, high blood pressure, joint problems and some cancers.

Go easy on fat.

Eating some fat is important for health but certain fats are better than others. Vegetable oils like olive or canola are your best choices because they are high in heart-healthy monounsaturated fats and low in the saturated fats that are associated with increased risk for conditions including heart disease and cancer. Limit foods that are high in saturated fats: animal products like fatty red meats and full-fat dairy products.

Concentrate on calcium.

Getting enough calcium (and vitamin D, see below) can help prevent osteoporosis, the leading cause of bone fractures in older adults (see our Bone Health Center). If you're 50 or older, you need 1,200 mg of calcium. Good sources of calcium include low-fat dairy products, calcium-fortified soymilk and orange juice, and fish with edible bones (like canned salmon or sardines). Other food sources of calcium include dark green vegetables, such as kale, broccoli and okra. If meeting your calcium needs through food seems daunting, talk with your doctor about whether you may need a supplement.

Don't forget about D.

Vitamin D, which you need to absorb calcium properly, is a unique nutrient in that it's available only in a few foods: fatty fish, egg yolks and fortified milk. We get most of our vitamin D through sun exposure: when UV light penetrates skin, skin cells produce a compound that the liver and kidneys convert to vitamin D. But as you age, skin becomes less efficient at synthesizing D. To meet increased needs with age, many experts recommend a supplement. (The recommended daily intake for people aged 51 to 70 is 400 IU; those over 70 need 600 IU-but many medical experts say that these recommendations are outdated and that most people, particularly those aged 50-plus, should aim for 1,000 IU.) Talk with your doctor about what's best for you.

"B" aware of changing nutrient needs.

As you age, your stomach produces less gastric acid, which makes it harder for the body to absorb vitamin B12-a nutrient that helps keep blood and nerves healthy-from natural food sources. (These include meat, fish, eggs and dairy products like yogurt and milk.) Since data suggest that up to one-third of older people can no longer absorb the vitamin from food, nutrition experts advise that people aged 50-plus get the recommended daily intake (2.4 mcg) of B12 from fortified foods, such as cereal or supplements. A multivitamin that supplies 100 percent the daily value should do you fine.

Keep moving!

It's never too late to reap the benefits of exercise. Research shows that regular exercise-at any age-not only helps prevent heart disease, diabetes, osteoporosis and some cancers, but also burns calories, gives you energy, relieves stress, helps you sleep better and improves strength and balance. What's more, studies show exercise increases blood flow to the brain and may even help new brain cells grow, which keeps the mind sharp. The key to reaping the benefits of physical activity is sticking with it, so choose any exercise you enjoy and aim for at least 30 minutes of moderate activity a day.

If you drink, do so in moderation.

Studies show that drinking moderate amounts of alcohol may protect against heart disease. But consuming alcoholic beverages may interfere with the effectiveness of certain medications. It also may increase the risk for some kinds of cancer. (The American Institute for Cancer Research recommends avoiding alcohol altogether.) It's important to weigh for yourself the risks and benefits. If you decide to drink, limit alcoholic beverages to no more than two drinks a day for men and one for women.

Play it safe with food storage and prep.

As you get older, your risk of foodborne illness increases (likely in part due to an aging immune system, say experts). Store and handle food properly (think: keeping your fridge at a safe temperature; avoiding cross-contamination in the kitchen). See more food safety tips.