Over 30? Here’s What’s Happening To Your Metabolism
Remember mindlessly scoffing down a whole pack of Tim Tams
in your teens and early 20s, with seemingly no affect to your waistline (or was
that just us?).
When you reach 30-something, the flat belly that comes
easily for teenagers and young adults may have gone hiatus and left you
wondering, why has my fast
metabolism checked out?
But even if you haven’t been lucky enough to win the
genetics lottery, you can make healthy lifestyle choices to love your bod deep
into your 40s, 50s, 60s and so on with a little know-how about your metabolism
and its role in your health.
What is metabolism?
Metabolism isn’t just an airy-fairy notion – it’s the biochemical
processes that continuously occur in your body to sustain life.
Your metabolism is responsible for converting the food and
drink you ingest into a usable source of energy to power literally everything
you do – from cell repair, hormone regulation, blood circulation and digestion
to thinking, breathing and singing your heart out on the drive
Most of us use the term ‘metabolism’ in the place of what’s
more accurately known as ‘metabolic rate’ – a measurement of how much energy
(kilojoules in food/drink) your body burns off over a period of time.
What is your basal metabolic rate?
Your basal metabolic rate (BMR) is a measurement of how much
energy your body requires to support basic, life-sustaining functions at rest.
The higher your BMR, the easier it is to keep a flat tum and
ward off the muffin top without significant physical effort. In fact, the
energy you use simply by being alive, contributes
to a significantly high percentage (around 60 to 75%) of your overall energy consumption.
What factors influence your metabolism?
There are many factors that affect your metabolism
including genetics, diet, sleep, body mass, gender and what we're going to focus on - age.
Hitting the big 3-0 isn’t a magic flip switch - your
metabolism naturally and gradually slows as you get older, starting as early as
Although these subtle
changes creep up on us and remain virtually unnoticed until at least our 30s, the
hormonal changes associated with age have a key impact.
Age and hormonal shifts
In your 30s, your pituitary gland in your brain starts decreasing
its production of human growth hormone (HGH) – it’s particularly important when
we’re young and developing but also necessary for building and maintaining
After the age of 30, men’s testosterone levels gradually decline,
but usually it’s not until reaching your 40s or 50s that you’ll experience noticeable
symptoms including a decrease in muscle mass and increase in fat storage.
For women, reaching menopause in your 40s or 50s triggers
one of the most significant hormonal shifts during your life - as estrogen
levels decline, muscle mass decreases and muscle quality drops.
What does your muscle
mass mean for your metabolism?
Muscle tissue requires about 3 times more energy to sustain than fat, so the
more muscle you have the greater the kilojoules expended at rest and the less
likely your body is to store fat in excess.
Sorry gals, but this is why men tend to have a faster metabolism than women – having naturally higher testosterone levels means an increased likelihood of developing and maintaining lean muscle mass.
But to keep it in perspective, when weighed up against your life-sustaining organs like brain, heart, liver and kidneys that are constantly working away to keep you alive, your muscles at rest only burn up a small portion of your daily kilojoules.
Quick fix metabolism-boosting
schemes are short term
There's tons of seemingly 'miracle cures' to boost your metabolism; drink hot lemon water, keep your smoothies green and lean, turn down the air
con to burn calories for temperature regulation, get your caffeine with a morning coffee fix or high quality dark chocolate (woohoo!), just to name a few.
These little changes may help marginally in the short term but let’s look at the big picture.
The big picture: Strength train to maintain muscle
Seeing as muscle mass deteriorates with time and inactivity, strength training like dumbbell exercises and kettlebell training are particularly valuable in maintaining muscle mass as we age, even if there is no magic, one-size fits all way to dramatically boost metabolism.
You don’t have to be a super buff gym junkie to do these
exercises either. Although heavy lifting and compound movements that activate
multiple muscle groups like squats and deadlifts may add to faster muscle
gains, more meditative exercises like yoga allow you to apply your own body
weight as a strength training tool. As always, balance is key.
Should you forget about
Is it time to say cardio, smardio? Nope, this doesn’t mean you should skip out on fat-burning, heart-friendly cardio exercises like running or cycling.
They won’t result in building as much lean muscle mass compared
to resistance training but performing exercise, particularly those that
require higher effort acts as a temporary metabolism booster.
As these exercises (at lower intensity) won’t continue to speed up your
metabolism all the way from your cool downs to cuddling up with an evening
cuppa, it’s important to do them regularly
and consider occasionally trading in your steady, long distance runs and their
endurance benefits for HIIT workouts (high-intensity interval training).
HIIT – Your time-saving,
High-intensity interval training involves short periods of
exercise nearly or at the full capacity your body is capable of (e.g. sprinting
at full-pelt) broken up by brief recovery periods (e.g. recovery jogs or walking)
and can be applied to both your gym sessions and on your runs.
With these all-in, crazy sweaty workouts, even after you’ve
stopped huffing and puffing your ‘oxygen debt’, or the amount of oxygen and
energy required to fuel recovery and return your body into a normal, pre-workout
state is considerably higher than it would be for longer, but less physically
It’s called EPOC (excess post-exercise oxygen consumption) and there’s a lot of sciencey stuff behind it, but basically it means high intensity sessions prolong the metabolism-boosting or ‘afterburn’ effect of your workout, even long after you’ve unlaced your running shoes.
To sum it up
A more muscular, fitter body maintained with regular
strength and cardio training has multiple benefits beyond increasing metabolism,
including keeping your bones strong and heart healthy later in life – not to
mention feeling empowered as you exercise your furry buddy without running out of breath, or lifting up your tiny tot with hulk-like strength without
But it is worth putting on your realistic thinking cap when
considering your metabolism – because everybody is different and multiple
factors are in play, including those you can control like eating lean muscle-building
protein as part of a balanced diet, and those you can’t like genetics.
Your body is unique, but we can all benefit from staying active and committing to healthy lifestyle choices now and in the future – so sweat it up and have fun!