India has one of the youngest retirement ages: 58-60 for most people and 65 for judges. This means that many active, intelligent people spend 15-20 productive years idly. This causes physical and mental deterioration.

Ageing occurs in all animals. In humans, it is believed to occur in part because stem cells stop regenerating damaged organs and the telomeres, or strands, in DNA shorten, and bits and pieces disappear. DNA is damaged and repair is no longer rapid and efficient. All these changes mean that the person becomes physically and mentally weaker.

How soon you age is both genetically and environmentally determined. You can be born with excellent genes but ruin everything by living in a polluted city and adopting bad lifestyle choices such as smoking, drinking, drug use and overeating (obesity).

The body starts to age around 40. Bones become weaker (osteopenia) and muscles deteriorate (sarcopenia). Almost half the muscle mass disappears by the age of 70. It is replaced by fibrous tissue and fat. This reduces physical strength, making one unable to lift even small weights, get up easily from a chair or climb a flight of 10 stairs.

Fat weighs more than muscle, so perceived weight gain often makes people go on a diet. Unbalanced nutrition, without the recommended amount of protein (0.8 grams per kilo of body weight) aggravates sarcopenia. Many people in India have diabetes. Insulin resistance increases with lack of muscle mass, resulting in poor diabetic control.

Sometimes, people take protein drinks, powdered supplements and vitamins in the belief that they will somehow reverse muscle loss and ageing. With the exception of Vitamin D3, folic acid, Vitamin B12 and iron supplements ( if necessary), most megavitamins and supplements are not needed.

Walking, jogging, cycling or swimming for 30-40 minutes a day six days a week works for cardiovascular fitness. Unfortunately, all the muscles are not used during these exercises. To offset wasting, neglected muscles also need to be worked out.

Housework and cooking are exhausting but not exercise. Women need to do aerobic exercise and weights to keep themselves physically fit.

Both men and women should train with light weights three times a week for 20 minutes to prevent osteopenia and sarcopenia. Before starting, get medical clearance. Get a professional trainer to teach you the proper technique.

Mental slowing can be tackled with mind games, new skills and memorising poetry and books.

Yoga provides a workout for the entire body, strengthens all muscles, improves posture and balance, and prevents falls. We need to go back to our roots to stay fit and healthy, and age gracefully.

The writer is a paediatrician with a family practice at Vellore and author of Staying Healthy in Modern India. If you have any questions on health issues please write to yourhealthgm@yahoo.co.in