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The metabolism myth & age related weight gain

Is age related weight gain inevitable? We often blame our weight gain on a 'naturally' slowing metabolism but the answer really lies with our lean muscle mass...

You've heard people say it, maybe you've even said it yourself: "at about 35 my metabolism slowed down, and the fat started to accumulate." The clear inference is that a slowing of metabolism is simply a part of aging, something we cant avoid, soemthing that is unfortunately inevitable, like night follows day. That's simply not true.

Men and women, on average, suffer from creeping obesity as they age. In the Western world the average 35-year-old male gains about a pound (half a kilogram) of fat mass each year until the sixth decade of his life. That means an average male will gain approximately 25 pounds or 12 kg between 35 and 60! Even worse, women often gain proportionately more. Why does this happen? The answer does lie with our metabolism, but the good news is that it's not unavoidable!

metabolism age weight gainUnfortunately human beings do tend to get fatter with age. Teenage or early 20's aged men average 15-20% bodyfat, whereas older men are usually about 25% or more. Women in their youth carry bodyfat of approximately 20-25% and usually move up to 35% or more by age 50. The reason for all this weight gain, however, is not an aging metabolism - it can be attributed in part to our lifestyle, activity levels, and the lean mass we have which in turn drives our metabolism.

The gaining of weight and the average figures above should not be accepted as normal because there is no biological reason for men and women to get fatter as they grow older. Increases in bodyfat are more a function of activity and lean muscle mass than age. So it's not our genetics that make us overweight, but simpy our lifestyle, and this is something we can change!

Inactivity results in loss of muscle, and a loss of muscle, not an aging metabolism, is the primary cause of creeping obesity. The muscle that remains is as metabolically active as ever, but in the majority of older people we simply have less of it.

Research backs this up

Researchers led by Dr. Ancel Keys at the University of Minnesota measured the energy requirements of people of different ages with different amounts of bodyfat. They found that the energy requirement of fat-free body weight (weight of the body minus the bodyfat) were remarkably constant for both men and women between the ages of 20 and 60. All the subjects, no matter what their sex or age, burned about 1.28 calories per hour per kilogram (2.2 lbs.) of fat-free body weight, under resting conditions.

So our metabolism or energy burning potential at rest is determined by our lean muscle mass whether we are young or old! To increase our lean mass we need to keep being active (eg walking, running, cycling, swimming, playing sport, etc) and preferably perform resistance / weights training to increase or maintain our lean muscle mass and metabolism.

What next?

Your next step should be to evaluate your lifestyle, training, and activity levels to see if there are any elements of this which you can change to get your metabolism going! Starting a fitness program is always a great idea, and you are never too old to start (at Complete we have trained clients 80 years for excellent health results!).

You may also like to read our other article on metabolism.

To find out more about weight gain, metabolism, fitness and strength training please contact us!


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