When it comes to weight loss, scientists believe it’s possible to exercise less, yet lose more weight.
Imagine a world where losing weight didn’t involve hours spent sweating in the gym, and excess kilos simply fell off. Where in 20 minutes you could burn more calories and lose more fat than you could after a week packed with time-consuming jogs.
Believe it or not, this idea isn’t far-fetched. This is the reality of high intensity interval training (HIIT) – an exercise regimen that asks for little of your time yet delivers maximum results. Scientists and exercise professionals around the world have built on years of research, and have proven the benefits of short bursts of intensive exercise.
How much exercise is enough?
Over half of all Australian adults are overweight or obese. It’s perhaps not surprising, 
therefore, that the diet and weight loss industries are thriving. From healthy home-delivered meal plans to enticing gym memberships and personal trainers promising long-lasting results, we’re constantly exposed to options to help us cut our calories and trim fat from our physique.
When it comes to getting physical, the Australian government recommends adults (those aged between 18 and 64) integrate at least 30 minutes of moderate-intensity physical activity on most, preferably all, days of the week. While the health benefits of moderate exercise are plentiful, when it comes to losing weight, an increasing body of research suggests you will do better to cut back on the length of time you commit to exercise whilst increasing the intensity of your workout.
A study published in the Journal of the American Medical Association followed the exercise habits of more than 34,000 women. It concluded that it took about an hour a day of moderate exercising to maintain weight. This research backed up by the findings of the (US-based) National Weight Control Registry, which reported that 90 percent of people who have successfully lost weight, and kept it off, exercise on average for an hour a day.
However, this research also tells us that even one hour of moderate intensity exercise every day is not enough to lose weight.
Workout for weight loss
A much more effective way to work out is to take part in high-intensity circuit and interval training. High intensity interval training refers to short bursts of high intensity exercise periods broken up by rest or relief periods and can be applied to any cardiovascular workout. In one study, Sydney scientists reported that sprint training for just 60 minutes a week burns the same amount of body fat as jogging for seven hours a week.
‘We’ve been searching for about 10 years for the minimum amount of exercise you can do with the biggest health impact factor,’ Dr Steve Boutcher, the lead researcher said when the study was published.
“Sprint training for just 60 minutes a week burns the same amount of body fat as jogging for seven hours a week”
Dr Boutcher, who is an exercise physiologist and associate professor at the University of NSW, believes the high-intensity training regime followed in the study provides the ideal amount of exercise intensity for health benefits, including weight loss, in a short time period.
As part of the program, participants sprinted on an exercise bike for eight seconds, and raised their heart rate to between 80 percent and 90 percent of its maximum rate, followed by 12 seconds of slow peddling.
‘In three 20-minute sessions a week, they’re only working hard for eight minutes,’ Dr Boutcher said.
Over the course of 12 weeks, most participants lost an average of 2kg of fat and gained 1.1kg of muscle mass in their trunk and legs.
During the study, scientists found that fast sprinting caused the body to release high levels of a specific group of hormones, called catecholamines, which drive the release of fat, especially abdominal and visceral fat, from fat stores so it can be burned by working muscles.
According to Dr Boutcher, lower intensity activities such as walking and swimming would not be capable of achieving the same results.
Why is HIIT more effective?
Exercise scientists used to believe that ‘steady state’ cardio exercise was superior for fat loss because relatively more fat is used by the body as fuel at lower exercise intensities than at higher intensities. You may burn more fat relative to glycogen when you go for a walk, but the total amount of fat lost during a walk is considerably less than if you train at higher intensities.
During these intensive workouts, the fat/glycogen ratio is lower, but you burn much more fat. Add this to the fact that interval training allows you to exercise at very high intensities for a much longer period of time, and you can see why HIIT is such a hit when it comes to weight loss.
As an added bonus, some research suggest there’s also an afterburn effect known as excess post-exercise oxygen consumption (EPOC), which means your metabolism and ability to burn calories increases for up to 24 hours after interval training.
Intervals also benefit your health
Whilst Boutcher’s research focused on the weight loss, a more recent British study revealed that short, sharp bursts of exercise are better at warding off heart disease than longer, less strenuous sessions.
Comparing men who took part in high-intensity sprints on an exercise bike with those who walked for half an hour on a treadmill, Dr Gray from Aberdeen University found that short bursts of intensive exercise spur the liver into taking in more fat from the blood, before storing it, or burning it off.
‘Our study showed that higher intensity shorter intervals of exercise might be a more effective method to improve health and reduce the time commitment to exercise,’ said Dr Gray.
As obesity continues to affect the nation’s health, the discovery that shorter bursts of activity can achieve outstanding results – both in terms of weight loss and overall health – gives hope that more of us may be inclined to exercise.
Sample Workout
Looking for a quick and effective workout? The ‘Tabata’ interpretation of interval training offers an easy way to integrate intervals into your workout regime.
Developed by exercise physiologist Izumi Tabata, the exercise protocol is based on 20 seconds of intensive training followed by 10 seconds of recovery for four minutes. Analysis of the results showed both anaerobic and aerobic improvements. While you can apply the Tabata technique to any exercise, we recommend starting off with the following exercises.
Remember, The key is to give it 100 percent during each 20 second interval,’ he says.
If you have any history of injuries, please consult your physical therapist and personal trainer before performing any of these exercises.
1. Killer sprawls: The sprawl is a full body movement that involves some of the largest muscles in the body. Start with a tuck jump, bend down and move into a push up position. Jump your legs back in and return to standing.
2. Mountain climbers: In a push up position, bring one leg forwards whilst keeping the other extended. Start the workout by kicking the extended leg forwards, moving the other back. To make the workout harder, keep the front foot floating off the ground.
3. Split lunges: Stand with your toes facing forward and your feet approximately one foot apart. Step your right foot out approximately three feet in front of your body. Slowly bend your right knee, lowering your body down to the ground. Push yourself back up to standing. Bring the right foot back to the starting position and repeat with your left foot.
