Use it or lose it.

I saw a great video the other day about perceptions of ageing. People in their 20s and 30s were asked what "old" means to them then asked to demonstrate how old people might do things, including walking, texting and exercising.

They're then surprised to be introduced to people in their 60s and 70s who are dynamic, fit and vibrant and who easily manage all the physically challenging things the younger people can do. To see the video, search for "disrupt ageing".

There's no doubt our idea of old has changed. Sixty is not what it used to be. Most people in their 60s and 70s don't consider themselves old and most are active and vibrant.


Many are also still working in some form, as the nature of work changes and the idea of retirement at 60 loses its appeal. Not everyone wants to spend their time in inactivity and the baby-boomer generation is far less inclined to sit quietly in the corner.

This is reflected in the desire for good health as we age.

We not only want to live long - we also want to be well for a long time. It only takes one health scare - a heart problem, cancer - to make us feel life is precious and strive to stay as well as we can for as long as we can.

A big part of healthy ageing is looking after our bodies. And a big part of that is how we nourish them.

As we get older we need to eat less, but we need to pack in more nutrition. We tend to need fewer kilojoules, but from 70 our bodies need more of things like calcium and protein. Our food needs to be more nutrient-dense.

Protein is really important as we age, because it helps maintain muscle mass.

This makes a big difference to our health. We naturally lose muscle as we get older - as much as 5 per cent of our muscle mass every decade after 30.

This is associated with other age-related changes: reduced strength, slowed metabolism, increased body fat, increased insulin resistance and lower bone density.

Eating meat, chicken, fish, dairy, eggs and plant-based protein like soy products helps maintain muscle.

The other key to this is exercise, particularly strength training.

Working with resistance helps maintain and build muscle - and this is important at any age.

Muscle mass protects us, in a way, from age-related physical decline.

A sign at my gym reads something like: Your body won't slow down if you don't.

This is pretty good advice. And if the fit, strong-looking people in their 60s and 70s I see there are anything to go by, it's never too late to start getting strong.

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