Business Insider has a piece smacks a very popular myth…that age-related weight gain is due to a “slowing” metabolism. Uh, not really. Most of the people who peddle this twaddle actually understand little or nothing about human physiology; they’re the same people who proclaim that after your lift weights and build a little muscle you somehow magically burns hundreds more calories per day than a mere mortal.

We move less as we get older. The behavioral reason is probably that our social groups and work change. The biological reason is less clear. It could be that we move less because it feels better to move less and our bodies shift into an unfortunate negative cycle of less movement reinforcing less movement. Or, it could be that something in our nervous or endocrine systems downshifts, and we move less because that internal regulatory change. It’s the movement that matters. Movement helps to bring your intake and output into alignment. It also provides irreplaceable mental, emotional, and physical health benefits.

If you choose not to move, the ill effects are on you. Don’t blame your “metabolism” for your own lack of will.

You’ve probably heard that once you hit 40, it’s all downhill when it comes to your weight. That inexplicable force we call our metabolism does begin to grind a bit slower every year from age 30 onward.

Source: The biggest reason you gain weight as you age has nothing to do with your metabolism