Forget eating salad or lifting heavy weights - there's a simple way of burning more calories.
Changing the pace of your walking can burn up to 20 per cent more calories than walking at the same speed, a study has found.
Calorie-burning estimations do not take into account the extra energy required to stop and start or change speed.
In light of this, people may be underestimating how many calories they burn while walking or playing sport, researchers revealed.
To burn even more energy from strolling, people should try to walk in a way that feels unnatural to them - in a curve, stopping and starting, or with weights attached to legs - they advised.
The study's author, Professor Manoj Srinivasan, of Ohio State University, said: 'Most of the existing literature has been on constant-speed walking. This study is a big missing piece.
'Measuring the metabolic cost of changing speeds is very important because people don't live their lives on treadmills and do not walk at constant speeds.
'We found that changing speeds can increase the cost of walking substantially.'
The very act of changing speeds burns energy, but that cost is not generally accounted for in calorie-burning estimations, Professor Srinivasan explained.
The researchers found that up to eight per cent of the energy we use during normal daily walking could be due to the energy needed to start and stop.
'Walking at any speed costs some energy, but when you're changing the speed, you're pressing the gas pedal, so to speak,' explained Dr Nidhi Seethapathi, another of the study's authors, also of Ohio State University.
Changing speed requires more work from the legs, and that process burns more energy, he added.
As part of the study, researchers measured how many calories people burned while changing speeds.
They asked people to change their pace on a treadmill while its speed remained steady.
People alternated between walking quickly to move to the front of the treadmill belt, or slowly to move to the back of the treadmill.
Prior experiments by other researchers changed the treadmill speed directly, which, it turns out, makes such experiments not applicable to real-world walking, Professor Srinivasan said.
When the treadmill speed is changing, the treadmill itself is doing some of the work, instead of the person walking.
The study also confirmed the researchers' prediction that people walk slower when covering shorter distances and increase their pace as distance increases.
This finding could have implications for physiotherapists, where measuring the speed it takes a patient to cover a certain distance is used as an indicator of their progress.
'What we've shown is the distance over which you make them walk matters,' said Dr Seethapathi.
'You'll get different walking speeds for different distances.
'Some people have been measuring these speeds with relatively short distances, which our results suggest, might be systematically underestimating progress.'
For more tips on how to burn more calories when walking, Professor Srinivasan, who is head of the Movement Lab at Ohio State University, offers some simple advice: walk in a way that feels unnatural.
He said: 'How do you walk in a manner that burns more energy? Just do weird things. Walk with a backpack, walk with weights on your legs.
'Walk for a while, then stop and repeat that. Walk in a curve as opposed to a straight line.'
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