Good nutrition is crucial to a healthy lifestyle. What many of us may not realise is that nutritional requirements change throughout our lives and that we need to eat based on our age.

"Good nourishment is necessary right from birth. If a child does not receive proper nutrition in the form of breast milk as an infant and high quality food as a toddler, chances are his development will be hampered," says Geetika Ahluwalia, dietician, Delhi Heart and Lung Institute.

As a baby metamorphoses into a child, and then a teen, his body's nutritional needs keep changing. These are dependent upon the interplay between the hormones and chemicals at that stage, and also those parts of his body that are still developing.

During the different stages and ages, we need to ensure a high quality diet based on these body requirements.

"While people should eat nutritious foods throughout their lives to maintain and protect their health, nutritional needs change as we age. So adjusting our diets based on age is important," says Geetika.

She adds, "The way we process vitamin B, for example, changes dramatically as we reach old age. Our body can still process it but really struggles to extract it from the food we eat, which is why a fruit rich diet is beneficial." Read on to find out about how to eat to stay healthy.

Age group: 13 - 20:
The teens are the time at which the body is at its peak. During adolescence, the metabolic rate of the body is very high, so whatever is eaten is converted to energy so anything goes, where food is concerned, as long as it's not fast food.

Proteins are essential for building the body and dairy products and non- vegetarian food is beneficial for people of this age. "Calcium is necessary for bone health as 45 per cent of the skeletal mass gets added during puberty and adolescence. Vegetarians should eat lots of paneer or soya in all forms," says Geetika Ahluwalia, dietician, Delhi Heart and Lung Institute.

Remember to keep fizzy drinks and tea and coffee at a minimum, as caffeine leaches calcium from the bones. Almost all the B vitamins play a major role in the release of energy from foods and are required for growth.

Bones are developing at this stage and increased amounts of vitamin D are needed to support bone growth. The diet of a budding adult must include plenty of vitamin A [ found in all orange and yellow fruits and vegetables], vitamin C [found in citrus fruits and red bell pepper], and vitamin E almonds and pistachio nuts] for healthy cell growth. Citrus fruits and amla should be an essential part of the diet.

Anaemia or low iron level is another health problem common in adolescents and weakens the immune system. The quickest way is to make iron- rich foods a part of meals is to add dried figs or raisins to salads and pureed soft tofu to soups or use spinach in the dal.

Health risks: Despite a healthy genetic makeup, many teenage boys experience poor growth and height because of their unhealthy diets and lack of physical activity.

Other health problems common in this age group are nutritional deficiencies, such as protein deficiency, which manifest at a later stage.

Many girls may develop unhealthy eating habits and eating disorders like anorexia, bulimia and binge eating. Iron deficiency is more common than expected and often goes undetected.

Mood swings and acne are also common among teenagers and should be kept in check by ensuring healthy diet and regular exercise.

Age group: 20s

Your 20s are the last chance to lay down new bones since by the time you are in your 30s you are stuck with the skeletal system you've got. What you eat this stage can help the body build itself.

Protein is necessary for tissue building as the body is subjected high stress levels and sometimes irregular meals often lacking in nutrition.

Concentrate on the starch food group at this age as these foods are high in fibre and give a satiated feeling that lasts long, decreasing the need to snack on junk. They are also the primary energy source for the brain and muscles. At the same time, eat potassium rich foods like bananas, potatoes with skin and mushrooms.

Vitamin C is especially important this time as it is an anti- stress vitamin absolutely necessary for this age as it is fraught with stress- and it also helps in the absorption of iron.

Health risks: It's the last chance to build bones, so if you are casual about your diet in these years you would be at risk of bone degenerative conditions.

Most women in this age group are deficient in iron and folic acid, which are essential during pregnancy as they prevent defects in the brain and spinal cord.

Other causes of concern for women in this age group are sexually transmitted diseases such as human papillomavirus (HPV), chlamydia.

Age group: 30s

Between rising dress sizes, a sagging body, and achy joints, the 30s seem to be an awakening for the years to come. The good news is that you're not yet old enough to just accept these aches and pounds as a course of nature. You can actually turn back the biological clock with food. "Health problems arise because our lives are more sedentary, even while our food intake remains the same," laments Geetika.

Cut down on fats and sugars drastically as well as making other healthy metabolism boosting changes that include replacing salty snacks with fruits and vegetables and switching from refined, white bread to 100 per cent whole wheat bread.

Most of us reach peak bone mass around age 30, meaning bones have reached maximum density. Therefore, after age 30, people need eat foods packed with bone-building nutrients such as calcium and vitamins D and K.

Health risks: Men in this age are too young to be at high risk for most diseases but those who carry on with their unhealthy eating and lifestyle habits increase their chances of developing lifestyle diseases.

Fertility in women begins to decline slightly and further deteriorates as she ages. This is also the stage at which women gain weight and develop pre-diabetes and thyroid gland problems.

Late thirties is the time when the rate of bone loss speeds up in many women.

Age group: 40s

Nuts are essential at this age, especially almonds as they can help lower cholesterol and reduce risk of heart disease as the body's immune system begins to slow down. One mistake made by people in this age group make is to cut back on carbohydrates completely. What they don't realise is that carbohydrates help generate the energy that the body needs and in its absence, proteins take over. Thus the work of the proteins-tissue building and cell regeneration-suffers.

Avoid eliminating the starch food group completely from your diet. These foods are high in fibre and give a satiated feeling that lasts long. Concentrate on fiber as it controls lifestyle disorders and is great for a sluggish digestion, which is another result of a sedentary life. Cranberries can help protect against bladder infections, and bananas can help eyesight.

Eat food rich in potassium like whole grains, fruits, and vegetables. They'll help you feel full on fewer calories, and they're also packed with disease-fighting phytochemicals.

Even though arthritis doesn't usually set in until later in life, the damage that causes the nasty disease happens in your thirties. Eat freshwater fish which reduces damage that might lead to arthritis as you stock up on the omega-3 fatty acids. Fish oils slow down cartilage degeneration and reduce inflammation. Also, preempt those fine lines that begin forming on the face by buying beans in bulk.

Health risks: This could be the decade of diseases for many men. If they have not maintained a healthy lifestyle, they are likely to be obese, have high blood pressure, high cholesterol, heart disease, and declining kidney and liver function.

The hormonal fluctuations of perimenopause in women start in the early forties.

It's the time when some women develop early stage of breast cancer or cervical cancer, which is the leading cause of death in older women in India.

Age group: 50s

Portion control and low metabolism are the buzzwords for this stage of life. This is also the age of deficiency related health problems where one must deal with the beginnings of the natural degeneration of the body. So make sure the food you are eating is nutritious and is in small quantities to facilitate better absorption of nutrients.

Get enough spinach since the lutein and zeaxanthinin this protect the eyes from age-related macular degeneration, the most common cause of ageing related blindness. Must-haves during this period include B vitamins, antioxidants, calcium and vitamin D. As estrogen levels decline, women are at an increased risk of heart disease, osteoporosis, and other agerelated health issues.

Important micronutrients like vitamins B6 and B12 help protect the heart and also help the body ditch a chemical called homocysteine that contributes to hardening of the arteries. Boost your B6 with bananas, potatoes, and pomegranates. And get B12 from eggs, fish, and chicken. Consider nuts your magic pills: Peanuts, hazelnuts and walnuts are loaded with vitamin E, an antioxidant that bolsters the immune system that might get run down as your run around.

The 50s are an important health milestone for women especially as they have to deal with menopause and symptoms of this life change can be eased with cashews, corn, apples, and soy, which are all great sources of phytoestrogens.

A burst of breast cancer -fighting antioxidants can be obtained from dark green, dark yellow, or orange fruits and veggies, like broccoli and brussels sprouts. Eat enough folic acid-rich foods like oranges, asparagus, and leafy green veggies. Bone up with low-fat dairy picks- milk, cheese, yogurt, and cottagecheese will give you a calcium boost.

Those who are in their 50s and more need to be careful to to eat only what they can handle, as they will not be able to digest food which is too rich even if it is highly nutritious.

Get your protein fix by eating a piece of grilled chicken with a small portion of saladthe roasted chicken and cold cuts will not only hamper digestion but also load the body up with salt. Dairy products in small quantities should definitely be included in the daily diet as the bones need all the support they can get: older people have a history of slipping and breaking bones.

Health risks: As men get older, their health concerns move on from heart disease and prostate cancer to incontinence, chronic lung conditions, stroke and Type 2 diabetes.

Heart disease, cancer, and osteoporosis are all major concerns for women but the most prevalent risks are breast, cervical and colon cancers.