A faster metabolism means quicker weight loss. But how easy is it? Dietitian Brooke Longfield asks leading nutrition experts how to rev up your metabolism.
‘I can’t lose weight, so I obviously have a slow metabolism.’ This is something that many of us have thought at some point. But is your metabolism really to blame for your weight woes?
Your metabolism is essentially your body’s engine. And your metabolic rate is the rate at which your body burns kilojoules. Your body uses up kilojoules even for simple things like breathing and pumping blood. Such basic bodily functions are what we call your resting metabolic rate, and they use up around 50–80 per cent of your daily energy (kilojoule) expenditure.
Your body also burns energy while digesting food, and this accounts for around 10 per cent of your total metabolism.
The remaining amount (roughly 20 per cent) is burned up whenever you are moving — whether it’s fast-paced, sweaty exercise or simply jiggling your toes.
“Some people are ‘fidgeters’ and burn up more energy just by the constant moving or twitching of their body,” says Dr Janet Franklin, senior clinical dietitian at Metabolism and Obesity Services at RPA Hospital.
Can you have a slow metabolism?
Like the engine of a car, some people’s metabolisms are more efficient than others.
“Everyone has a different metabolism, just as everyone’s genetic predisposition differs,” says Dr Helen O’Connor, accredited practising dietitian and senior lecturer at Sydney University. “For instance, some people have lower resting metabolic rates relative to their body weight, and this may predispose them to gaining weight more easily.”
Dr Franklin agrees. “Genetics does play some sort of role in our metabolism. Some people are able to burn up the equivalent energy expenditure of a 10km run just by going about their everyday life.”
Do thin people have a faster metabolism?
No, in actual fact, larger bodies have higher resting metabolic rates than lean ones, as they have more muscle and bigger organs that require more energy just to keep them working.
“When someone is carrying around extra weight, the energy required to move that weight is quite significant,” explains Dr O’Connor.
How can I speed up my metabolism?
While there’s no quick fix, it is possible to achieve a faster metabolism. You’ll need to make a number of changes to your routine, and stick to them each day until they become second nature to you, like new healthy habits. In combination, these changes will help you burn more kilojoules on a daily basis.
1. Move more
Using your muscles in absolutely any way means you’re burning up kilojoules. As we’ve discovered, even fidgeting helps. But moving more doesn’t have to mean getting to the gym more often. Start by trying to increase the amount of incidental or unplanned activity you do each day, so you’ll burn more kilojoules without even trying. For instance, take the stairs instead of the lifts. Also, household chores like vacuuming, dusting and washing the car are all big kilojoule burners.
At work, make an effort to get out of your chair every half hour. Just standing up uses more energy than sitting down!
On top of this, you need to put half-an-hour of heart-pumping exercise into your daily routine. The best way to do this is to find something you love doing, so you will want to stick to it.
If you like meeting people, join an outdoor walking group or sign up to a group exercise program. If a quieter pace is more your thing, try yoga or spend more time doing moderate to heavy gardening.
An effective way to speed up your metabolism is to increase the amount of muscle tissue you have. This is because muscle burns about four times more kilojoules than fat tissue. “The more muscle you have, the more energy you burn, so therefore your metabolism will be higher. That’s why men tend to burn up more energy than women,” says Dr Franklin.
Resistance training is a great way to build and maintain muscles. It doesn’t have to include lifting heavy weights; just using your own body weight counts as resistance training. For example, try doing squats, lunges, push ups and tricep dips. Resistance bands are also effective for building muscles, or you can join a Pilates or yoga class.
3. Lose weight but don’t crash diet
Losing weight is achieved by eating fewer kilojoules than you burn off, but beware that severely restricting kilojoules can have the reverse effect.
There’s mounting evidence that drastic dieting can actually slow your metabolism. “Quite simply, your body’s survival instinct kicks in and it goes into starvation mode,” says Dr Franklin.
When faced with extreme hunger, your body “protects and holds on to fat stores because it doesn’t know when the next time food will be available. Instead, the body uses muscle as fuel, causing loss of muscle mass, which slows down your metabolic rate. Not good news if you’re trying to lose weight,” explains Dr Franklin.
Extreme dieting also causes your body to crave high-kilojoule foods. “When the body detects that it’s losing a lot of weight, a whole range of hormones are released. These hormones trigger your appetite so that you go and seek food. And we’re not talking lettuce here; it’s high-energy, carb-rich foods that the body wants,” explains Dr Franklin.
Then, after coming off a crash diet and returning to normal eating habits, your metabolism will have become slower, so you’ll gain weight more easily than before dieting.
Most experts agree that a gradual and steady loss of between 500g and 1kg per week is a healthy, safe amount of weight to lose. For the average person, this can be achieved by reducing the amount of kilojoules you eat each day by around 2000kJ (500cal). See our seven-day meal plan (Downloads, below) that is based on a daily intake of 6300kJ (1500cal), which will result in steady weight loss for the average adult. We’ve formulated this weight-loss meal plan so that you can still eat three tasty meals a day and enjoy healthy snacks, all while you gradually lose weight.
Metabolism – does it slow with age?
Yes, it does. “The main reason this happens is because we lose muscle mass as we age,” says Dr Janet Franklin, Senior Clinical Dietitian at Metabolism and Obesity Services at RPA Hospital. This is usually because we are less active. Also, the changing hormones after menopause promote fat storage in women.
So, by carrying more fat and having fewer muscles, an older woman will have a slower metabolism.
Our four-week program (see downloads, below) includes a mix of long walks; short, steep walks; and interval sessions, plus a few resistance sessions. This combination will give you the best metabolic improvements, and also beat boredom, so you’re more likely to stick to it!
The biggest loser effect
It makes dramatic TV to see contestants shed 50–60kg. But what happens to the weight when filming stops?
An explosive study published earlier this year tracked the fates of 14 contestants on the US version of The Biggest Loser for six years after they left the top-rating show. Sadly, all but one contestant has regained most of the weight they had lost on the show; and four now weigh more than they did before going on the show.
Moreover, the metabolic rates of these contestants have dramatically slowed, so they now burn 2000kJ (500cal) per day less than others of the same weight.
Not only does this highlight the fact that drastic dieting doesn’t work, but it also suggests that you may be causing long-term harm to your metabolism as well.
The bottom line
A proven and safe way to improve your metabolism is to increase your muscle mass, which means you burn more kilojoules, and lose weight on a gradual basis.