Simply believing you are exercising can help you become thinner, researchers say.
Those who do physically demanding jobs and are aware of the potential health benefits of their work lose more weight and have lower blood pressure than those who do the same jobs but do not realise the positive side-effects.
Researchers concluded this was because some benefits of exercise are down to the placebo effect, which is often seen in medical trials when patients respond to dummy pills as if they were taking the real drug.
Psychologists at Harvard University studied 84 women who worked as hotel housekeepers, cleaning rooms and changing sheets.
They found many were worried that they were not doing enough exercise, even though their jobs are physically demanding. The researchers pointed this out to half the women, telling them they were doing enough exercise through their job to lose weight and stay healthy.
The housekeepers were even told how many calories they were burning doing specific tasks.
For example, changing linens for 15 minutes burned 40 calories, vacuuming for 15 minutes burned 50 calories and cleaning bathrooms for 15 minutes burned 60 calories.
The other half were told nothing about the health benefits of their daily chores. After four weeks, those told they were doing lots of exercise at work had lost two pounds on average, lowered their blood pressure by almost 10 per cent, and shed almost 0.5 per cent of their body fat.
The other group experienced no noticeable changes in their health or physique, according to the study published in the journal Psychological Science.
Lead researcher Ellen Langer said there was no apparent difference in activity levels of the two groups, claiming: "The changes were a function of the change in mindset alone.
"If you can put the mind in a healthy place, you can have dramatic physiological consequences. If the mind is fully in a healthy place, the body will be as well."
But she added: "Our mindsets are hard to change. So if you're just sitting on the couch and just telling yourself that you're exercising, you're not going to believe yourself and so there will be no change."
http://www.mailonsunday.co.uk/pages/...n_page_id=1798
