Your body is hardwired to be as lazy as possible

You may think you've earned that post-run doughnut, but you might not have burned as many calories as you think, according to a new study. 

Scientists have found the human nervous system is wired to save energy and will adjust our movements to burn less calories while we're doing a physical activity—all without us realising. 

In other words, our body will try to do everything in the laziest way possible.

"Many of us perceive that we're consciously lazy, but that seems to extend down to our subconscious nervous system," one of the authors of the study Max Donelan, a neuromechanist at Simon Fraser University in Canada, told the New York Times.

Researchers analysed the walking patterns of nine participants who wore robotic exoskeletons. The equipment allowed researchers to control resistance to their knees, by making it harder or easier to swing the legs—but the variance was programmed to be so slight that participants wouldn't consciously notice.

They found that the subjects were able to adjust their gait in real-time to use as little energy as possible, even if their own walking style had been established over decades. They even made these shifts when energy savings were quite small, as low as five percent.

What does this mean for the exercise set?

If you're sweating to burn calories, you'll come up against the body's opposite goal of conserving energy. However if you're a marathon runner, this internal mechanism may work in your favour.

"Are you trying to lose a pound or win a race?" lead researcher Jessica Selinger told CBS news.

"You might wish that you were less efficient so that as you exercise you're burning more calories per movement… if you're running a really long running race you want to be able to conserve some of that energy for the end of the race so that you can have that final push."

While your fitness trackers may indicate you're burning the same amount of calories each session, it's important to bear in mind that your central nervous system will adopt to the most efficient movement pattern and, as a result, the body will burn fewer and fewer calories as it adjusts to routines.

These findings were published in the journal Current Biology.