Like a favourite car that's starting to show its age, many of us begin to put on weight as we get older.

"She's not what she used to be!" I heard a friend say the other day as he lovingly slapped his belly in the way one gives the hood of their old clunker an affectionate tap.

Many people blame a sluggish metabolism for the weight gain. But as it turns out, our metabolism isn't the real culprit when it comes to the weight that seems to creep on with each passing decade.

In fact, age-related weight gain has far more to do with our activity patterns than it does with our metabolism, which barely budges after age 30, according to the National Institutes of Health.

'Boosting your metabolism' is a myth

Our metabolism, the term for the calorie-burning process our bodies do naturally, shifts based on the various activities we do throughout the day.

Unfortunately, the rate at which we digest our meals and burn energy can't be altered significantly enough to cause weight loss. (No, spicy foods and green teas won't move the needle.)

But as we age, we also get less active while sticking to roughly the same diet. Researchers say that this – not our metabolic rate – is the real culprit for the extra weight we pack on as we get older.

Instead, move more

To avoid weight gain, adding regular movement to your day is crucial. That could involve taking the stairs at work or hitting the gym a few times a week – every little bit counts.

In fact, new research published this spring suggests that to achieve better health and reduce your risk of death from any cause, any kind of movement is better than little or none.

That means any effort that gets you moving and breathing – whether it's a twice-weekly heart-pounding kickboxing class or a 30-minute walk to work – has measurable benefits for your brain and body.

That study, published in the Journal of the American Heart Association, used data on physical activity and death rates from national surveys of more than 4,800 adults.

It found that people with more "bouted" or concentrated activity (like a fitness class or gym session) fared no better than people who clocked the same amount of exercise in tiny bits throughout the day (like walking to the train or taking the dog for a stroll).

"The key message based on the results presented is that total physical activity (i.e., of any bout duration) provides important health benefits," the study's authors wrote.

This article was originally published by Business Insider.

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