When you change speed on the treadmill or cross-trainer, have you ever noticed the reading on the display about the level of METs you are working at?
It’s worth paying attention, as this is a measure of how fast your metabolism is ticking over while you work at that intensity. This week we’re taking a look at the engine of your body, your metabolic rate. Here’s how measuring your MET hours can help you crank it up.
Convince your body to burn energy more quickly and not only will you churn through calories faster, you will be a more efficient and healthier machine.
Boosting your metabolism
Your busy body consumes energy all the time, even when you’re sleeping. The rate at which you do so is unique to you, and influenced by such factors as the amount of muscle you carry, your heart rate, your age and your gender. It is known as your metabolic rate and its level of activity when you are at rest is known as your basal metabolic rate, or BMR. The fitter you are, the speedier your BMR will be. If you think yours could be slightly sluggish, there is plenty you can do to give it a push.
- Interval training is an effective way to raise your heart rate. It involves alternating short bursts of intense aerobic work with more moderate activity and recovery time. Working out this way means that your body continues to burn calories at a higher level for more than an hour after you finish.
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Building muscle also speeds up your metabolism. According to Dr Pamela Peeke from the University of Maryland in Baltimore, muscle burns up to five times more energy than fat. Half a kilo of muscle burns 25 to 50 calories a day, while half a kilo of fat burns just 5 to 10. The more muscle you have, the more calories you’ll burn.
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Eating enough food is another factor to consider, especially if you are restricting your calories. When you fast or don’t eat for many hours, your metabolism slows down to conserve energy. This makes it harder to lose weight. Starving yourself is not the answer to your weight problems. Eating healthy, low-calorie food and improving your general fitness is the solution. And this is where MET minutes come in.
The MET question
Every move you make can be measured as a multiple of your BMR, known as METs (metabolic equivalent of task). At complete rest your body will burn energy at the rate of 1 MET. A 4 MET activity burns four times the energy used by the body at rest. If you do a 4 MET activity for 30 minutes, you have done 120 (4x30) ‘MET minutes’. But you could also work up 120 MET minutes by spending 15 minutes doing an 8 MET activity.
A major international study* found that notching up 500 to 1,000 MET minutes a week has substantial health benefits and boosts your BMR. Of course, keep moving beyond 1,000 minutes and you’ll see even more results. Even if you shift from an inactive lifestyle to fewer than 500 MET minutes a week, you’ll still see some improvement.
Intent on intensity
The METs system allows you to calculate ‘absolute intensity’ rather than the ‘relative intensity’ we measure with the subjective perceived rate of exertion scale. As it provides greater accuracy, it is a useful gauge of how your fitness is improving.
Sitting at a desk, driving, watching TV, cooking and ironing all fall into the light intensity category with a METs level of between 1.1 and 2.9. But most of your planned activity should fall into the moderate or vigorous category.
Moderate mindset
Moderate exercise is defined as 3 to 5.9 METs. If you stick within that moderate range, chalking up 1,000 MET minutes will take 166 to 334 minutes – that’s up to five and a half hours. If you have the time and don’t like vigorous exercise, there’s nothing wrong with this, but mixing up the intensity will produce the same results more quickly. Here are some examples of moderate exercise:
- Walking, at a moderate or brisk pace (5-7 kph) on a level surface
- Walking downstairs
- Hiking or bush walking
- Cycling, 8-14 kph on a level surface
- Yoga
- Trampolining
- Weight training using free weights
- Boxing using a punching bag
- Ballroom dancing
- Table tennis
- Tennis doubles
- Golf
- Recreational swimming
- Moderate housework (cleaning floors, hanging laundry)
Feel the burn
Vigorous exercise is defined as 6.0 METs or more and working within this range slashes the amount of time you have to spend in the gym to reach your weekly 1,000 MET-minutes target. For example, if you exercise at a 10-MET level, you only have to do 100 minutes a week – 1 hour 40 minutes – to reach your quota. This kind of exercise burns more than 7 calories a minute, so get moving!
- Racewalking and aerobic walking (8kph or faster)
- Jogging or running
- Walking briskly uphill
- Rock climbing
- Cycling (16kph or faster)
- High-impact aerobics
- Vigorous calisthenics, such as push-ups or pull-downs
- Karate, judo, jujitsu
- Circuit weight training
- Boxing, sparring
- Tennis singles
- Most competitive sports, such as football, basketball and soccer
- Swimming laps
- Heavy housework (moving furniture, carrying objects up and down stairs)
Week by numbers
It’s important to measure your progress towards your health and fitness goals to keep you focused. Aiming for 1,000 METs minutes a week gives you a clear target to reach so you can be sure you are doing enough exercise to become fitter and burn more calories. This will boost your BMR nicely and make your entire system function more efficiently, improving your overall health. Spend 10 minutes sprinting at level 10? That’s 100 MET minutes – meaning you have 900 to go!
* 2008 Physical Activity Guidelines for Americans