Scientists have shed new light on the challenges facing exercise professionals in getting the population moving, after new research showed that obesity causes people to see distances as farther than they actually are.

The findings from the Colorado State University study paint the picture of a ‘vicious circle’ which means exercise appears more challenging as weight increases. Tests showed that a a 330lb person saw a 25m distance as 30m, while a 130lb person saw that same distance as 15m. The effect also applies to hill gradients, meaning heavier people will be more inclined to choose an elevator over climbing the stairs.

“You’re not seeing the world as it is, you’re seeing the world in terms of your ability to act,” said Dr Jessica Witt, psychologist at Colorado State University, at the annual meeting of the American Association for the Advancement of Science, in Washington DC.

“We think that these perceptual biases can create a vicious circle for people with obesity. It is conscious perception of the world. But it’s not based on conscious perception of the body or feelings of laziness.”

The phenomenon is thought to stem from a survival mechanism in early humans designed to help quickly evaluate our ability to tackle testing situations. However, the reflex appears to be counter-productive in persuading overweight people to be more active.

To overcome this, researchers suggested setting easier targets for obese people at the beginning of exercise regimes to avoid early discouragement. Use of telescopic glasses to change perceptions of distance was also mooted.