| Is metabolism something were stuck with for life- really just the luck of the draw in the genetic lottery or can we rev it up with the right know-how?
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On the face of it, it is a simple equation: energy in and energy out. But lets take a closer look at the mechanics of metabolism. Its the amount of energy ones body burns in a day. If energy in equals energy out, youve got a body operating in equilibrium. Were all supremely adept at the "energy in" part- fuelling our bodies with food. But how exactly do we use the energy? Our bodies use the energy from food in three ways: physical exertion, the digestive process and cellular activities.
COUCH POTATOES REJOICE
Whether we are idly flicking the channels on the remote control or pushing our bodies beyond their physical limits, we are burning energy. For an average person, activity accounts for 20 to 30 per cent (approx) of total energy expenditure. Rest can knock it down to 10 per cent and exercise can increase it up to 5O per cent. Energy acquisition in the form of eating is not just about taking energy in. A lot of energy is used for digesting, processing and metabolising the food into useable substances. The body prioritises these processes, which probably explains why the couch develops such a magnetic pull after a bout of serious overindulgence. This essential conversion of food accounts for almost 10 per cent of our total energy expenditure. By far, the maximum energy (60 to 70 per cent of total energy expenditure) is used in the effort required to maintain life-fuelling processes at the cellular level that keep us alive and kicking.
A GOOD LOAD OF NOTHING
Paradoxically, our resting metabolic rate is the calories we burn just lying around seemingly doing nothing. Consider two people comatose on a couch: The person with the high resting metabolic rate will burn more energy than the person with a low one. Seems unfair, doesnt it? But there are lots of things that contribute to resting metabolic rate. For instance, our genetic make-up, gender, height and age. But there are other factors, especially muscle-to-fat ratio, that also play a part, over which we have some control, Muscle is more metabolically active than fat tissue. In fact, one kilogram of muscle bums up to nine times the calories of one kilogram of fat. So, altering your fat-to-muscle ratio with resistance training can raise your resting metabolic rate by as much as five per cent.
REST IS THE KEY
When the chips of our genetic and biological heritage are down, this is our only bargaining card to increase the resting metabolic rate. Testosterone is the hormone integrally involved in building muscle, and as any bar brawl will attest, men have far more of it than women. With more testosterone and greater muscle mass, mens metabolism is stoked up to fire a little faster than womens.
But if a woman is tall and slim, her resting metabolic rate will be higher than that of a short-and-wide booby prize, only because of her higher body mass.
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